Section 1 The Fish Body - Jourdanton ISD · students to the characteristics of fishes and their...

OverviewBefore beginning this sectionreview with your students theobjectives listed in the StudentEdition. This section introducesstudents to the characteristics offishes and their special adaptationsto life in water.

K-W-L Have students make shortindividual lists of all the thingsthey already Know about fish.Then have students list things theyWant to know about fish. Havestudents save their lists for lateruse in the Reteaching at the end ofSection 1.

DiscussionWrite the following words on theboard: starfish, sea horse, sea cow,lamprey, eel, and stingray. Ask stu-dents to identify which organismsthey think are fish. Ask students towrite down whether it is a fish ornot and why. (The starfish is not afish—it is an echinoderm; and the seacow, or manatee, is also not a fish—it is a mammal. The sea horse,lamprey, eel, and stingray are all fish. This demonstrates that fishesare a very diverse group of organismsthat all share important characteris-tics the students will learn about inSection 1.) VerbalTAKS 2 Bio 8C; Bio 8B

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746 Chapter 33 • Fishes and Amphibians

• Lesson Plan• Directed Reading• Active Reading• Data Sheet for Data Lab GENERAL

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TT BellringerTT Respiration in FishesTT Fish Heart Structure

Section 1 The Fish Body

Key Characteristics of Modern FishesWhat makes a goldfish instantly recognizable as a fish? You mightname characteristics such as its fins, gills, scales, and typical fishshape as traits that contribute to the goldfish’s “fishiness.” Butsome fishes don’t look quite so fishy. This is because the term fishrefers to any member of one of three general categories of verte-brates: Agnatha (jawless fishes), Chondrichthyes (cartilaginousfishes), and Osteichthyes (bony fishes). The great diversity of fishesfound today reflects various adaptations that enable fishes to live inthe oceans and fresh waters around the world. Fishes vary in sizefrom whale sharks longer than a moving van to gobies no largerthan your fingernail. Despite the variation seen among fishes,shown in Figure 1, all share certain key characteristics.

1. Gills. Fishes normally obtain oxygen from the oxygen gas dis-solved in the water around them. They do this by pumping agreat deal of water through their mouths and over their gills.

2. Single-loop blood circulation. Blood is pumped from the heartto the capillaries in the gills. From the gills, blood passes to therest of the body and then returns to the heart. (Lungfishes,which have a double-loop circulation, are an exception.)

3. Vertebral column (backbone). All fishes have an internal skele-ton made of either cartilage or bone, with a vertebral columnsurrounding the spinal cord. The brain is fully encased within aprotective covering called the skull or cranium.

To learn about one common fish, read Up Close: Yellow Perchlater in this chapter.

Objectives● Describe the characteristics

of modern fishes.

● Summarize how fish obtain oxygen.

● Summarize how bloodcirculates through a fish.

● Contrast how marine andfreshwater fishes balancetheir salt and water content.

● Describe two methods ofreproduction in fishes.

Key Terms

gill filamentgill slitcountercurrent flownephron

Sea horse

Stingray

Trout

Figure 1 Fish diversity.While these three fish appearquite different externally, theyshare a number of characteristics.

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Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TEKS Bio 8C, 10A, 11A

Teacher Edition TAKS Obj 2 Bio 8C TAKS Obj 4 IPC 9D TEKS Bio 3E, 8B, 8C, 12CTEKS IPC 9D

pp. 746–747

Using the FigureHave students locate the portion ofFigure 2 that shows countercurrentflow. Point out that water flowsover the fish’s gill from front toback. At the same time, the bloodin the capillaries in the gills flowsfrom back to front. Explain thatthis arrangement permits gasexchange to occur all along thecapillaries in the gills. If the waterand blood flowed in the samedirection, the oxygen content ofthe two equilibrate at about 50percent saturation, far lower thanin countercurrent flow. Visual

Teaching TipUnderstanding CountercurrentFlow Have students make a chart,dividing their paper into twocolumns: same direction flow andopposite direction flow. Each col-umn should be further subdividedinto O2 in water and O2 in fish.Have students record 80% O2saturation in water and 20% O2saturation in fish gill capillaries forboth flow directions. Assume that10% of the O2 can be exchanged bydiffusion for each subsequent chartrow (representing a certain length ofgill capillary). Under same directionflow, the next row would be 70%in the water and 30% in the fish.What is the maximum O2 contentthat can be achieved in this fish if ithad a same direction flow? (50%;both fluids continue their respectiveincrease and decrease by 10% inter-vals until there is no furtherconcentration difference at 50%.)To complete the other part of thechart, students need to realize thatthe O2 content of water remains at80% since new water is continuallypassing over the gills. The secondrow under opposite direction flowwould be 80% and 30%. What isthe maximum O2 content that canbe achieved if the fish had an oppo-site direction flow? (80%; O2 contentin the fish increases by 10% intervalsuntil there is no further difference inO2 content at 80%.) LogicalLS

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Chapter 33 • Fishes and Amphibians 747

StrategiesStrategiesINCLUSIONINCLUSION

Have students research the fish known asthe sea horse. Students should give an oralreport to the class that includes the charac-teristics of this fish, descriptions or picturesof different species of sea horses, and adescription of the life cycle of the sea horse.In the course of their research, students mayencounter other fishes that do not necessarilylook like a “typical” fish. Encourage studentsto report on these fish as well. Bio 12C

• Learning Disability • English as a SecondLanguage

GillsOne challenge faced by all animals is the need to get enough oxygen for cellular respiration. Sponges, cnidarians, many flatwormsand roundworms, and some annelids obtain oxygen by diffusionthrough the body surface. Other marine invertebrates, such as mol-lusks, arthropods, and echinoderms have gills, which are specializedrespiratory organs. Fishes also respire with gills.

If you look closely at the face of a swimming fish, you will noticethat as it swims, the fish continuously opens and closes its mouth, asif it were trying to eat the water. What looks like eating is actuallybreathing. The major respiratory organ of a fish is the gill, shown inFigure 2. Gills are made up of rows of —fingerlikeprojections through which gases enter and leave the blood. The gillfilaments hang like curtains between a fish’s mouth and cheeks. Atthe rear of the cheek cavity is an opening called a . When afish “swallows,” water is forced over the gills and out through the gill slits.

This swallowing procedure is the core of a great change in gilldesign shown by fishes—countercurrent flow, also shown in Figure 2.In , water passes over the gills in one directionas blood flows in the opposite direction through capillaries in thegills. Countercurrent flow ensures that oxygen diffuses into the bloodover the entire length of the capillaries in the gills. Due to thisarrangement, the gills of bony fishes are extremely efficient respira-tory organs. Fish gills can extract up to 85 percent of the oxygen inthe water passing over them.

countercurrent flow

gill slit

gill filaments

Figure 2 Fish gill structure. Countercurrentflow increases the gill’s efficiency.

Water flowacross filaments

(front to back)

Blood flowin capillaries

(back to front)

Respiration in Fishes

1 Oxygen-rich water enters the fish’s mouth and passes over thegills as it exits through the gill slits.

2 Each gill is composed of rows of gill filaments, which have thin membranes through which oxygen and carbon dioxide can diffuse.

3 Water passes over the filaments from front to back. Blood circulates throughthe filaments from back to front. When bloodenters the filaments, its oxygen content islow (blue). When it exits the filaments, itsoxygen content is high (red).

Gillfilaments

Gillfilaments

Gill slit

Water flow

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IPC Benchmark Fact

Several factors affect the amount of oxygen gasdissolved in the water around fish, includingtemperature and pressure. Remind students that as temperature increases, a solvent holds lessdissolved gas. In addition, as pressure increases, a solvent holds more dissolved gas. Ask studentwhere a higher concentration of dissolved oxygengas is likely to be found, near the surface or deeperin the water? (Higher concentrations of dissolvedoxygen will be found in deep water because thetemperature decreases and pressure increases asone moves into deeper water.)TAKS 4 IPC 9D (grade 11 only)

Demonstration To demonstrate the simple tubular“heart” of ancestral chordates, usean aquarium siphon (available atpet stores) that has a bulb attachedto it. Insert a small piece of rubberor glass tubing into the siphon tokeep the valve open. Place the endof the siphon in a jar of coloredwater and fill the rest of the tubewith water. Place the other end ofthe siphon in another jar contain-ing an equal volume of clear water.Squeeze the bulb, representing theprimitive “heart,” to show howblood is inefficiently moved in bothdirections. Water will flow out inboth directions, and when the bulbis released, water will be sucked infrom both ends. The level of eachjar will go down very slightly whenthe bulb is squeezed and rise anequal amount when it is released.You can also demonstrate the valueof valves by showing the efficiencyof the pump when the valve isoperating properly. With the valveenabled, water will move from onejar to the other. VisualTAKS 2 Bio 10A; Bio 3E

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Teach, continuedTeach, continued


CareerCareerAquaculturist Aquaculture, or fish farming,is one of the fastest-growing sectors of agricul-ture. Both freshwater and saltwater species canbe raised commercially. Operating a fish farmrequires a knowledge of how to keep the fish’senvironment clean, proper feeding techniques,and how to control fish infections, such asthose caused by bacteria and parasites. Bio 3D

Invite a chemistry teacher to your class todiscuss the amazing chemical properties ofwater. Topics could include cohesion, surfacetension, heat of vaporization, heat of fusion,polar covalent and ionic bonds, and therelationship between the temperature anddensity of water. IPC 9D (grade 11 only)

CHEMISTRYCHEMISTRYCONNECTIONCONNECTION

Circulation of BloodChordates that were ancestral to the vertebrates had a simple tubular“heart.” This structure was little more than a specialized zone ofone artery that had more muscle tissue than the other arteries had.When a tubular heart contracts, blood is pushed in both directions,and circulation is not very efficient.

For an organism with gills, such as a fish, a simple tubular heartis not an adequate pump. The tiny capillaries in a fish’s gills createresistance to the flow of blood, so a stronger pump is needed toovercome this resistance. In fishes, the tubular heart of early chor-dates has been replaced with a simple chamber-pump heart, shownin Figure 3. The chamber-pump heart can be thought of as a tubewith four chambers in a row.

1. Sinus venosus (SIE nuhs vuh NOH suhs). This collection cham-ber acts to reduce the resistance of blood flow into the heart.

2. Atrium. Blood from the sinus venosus fills this large chamber,which has thin, muscular walls.

3. Ventricle. The third chamber is a thick-walled pump withenough muscle tissue to contract strongly, forcing blood to flowthrough the gills and eventually to the rest of the body.

4. Conus arteriosus (KOH nuhs ahr TIHR ee oh suhs). This cham-ber is a second pump that smoothes the pulsations and adds stillmore force.

The fish heart represents one of the great evolutionary changesfound in vertebrates—a heart that pumps fully oxygenated bloodthrough a single circulatory loop to the body’s tissues.

Figure 3 Fish chamber-pump heart. These foursteps show how blood flowsthrough the heart of a fish.

Fish Heart Structure

Contractions of the ventriclepump the blood toward the gills.3

Oxygen-poor blood from thebody enters the sinus venosus.

From there it moves into the atrium.

1 The atrium deliversblood to the ventricle.2

The conus arteriosussmooths the pulsations

of the bloodstream.

4

Sinusvenosus

Atrium

VentricleConus

arteriosus

The term sinus venosus isLatin, as are many anatomi-cal terms. The Latin wordsinus means “bend,” andthe Latin word venosusrefers to veins. The sinusvenosus is a bent collectingchamber that conductsblood into the heart.

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Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B (grade 11)TAKS Obj 3 Bio 7B TEKS Bio 4B, 7B, 8C, 10A, 10BTEKS Bio/IPC 2C

Teacher Edition TAKS Obj 2 Bio 4B, 10A TAKS Obj 4 IPC 9DTEKS Bio 3D, 3E, 4B, 10A, 11A, 12CTEKS IPC 9D

pp. 748–749

DemonstrationThe day before this lesson, fill twobeakers with distilled water. Addone tablespoon of salt to onebeaker and mix well. Cut twoequal lengths of potato. Put onepotato piece in each beaker, and letit sit overnight. The next day, tell students that each potato piece rep-resents a freshwater fish. Tell themone fish has been placed in freshwater, and one has been placed inthe ocean. Remove the potatopieces, and let students observeeach. Ask students which “fish”was in the ocean. (the limp one)Ask them how they arrived at theirconclusions. (In the ocean, the waterconcentration was greater in thepotato than in the beaker, so waterdiffused out of it; the opposite is truefor the freshwater potato.) Ask stu-dents why fishes have difficulty living in water environments otherthan their own. (They would needsome mechanism to regulate theirwater and salt concentrations.)

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Analyzing IonExcretion in Fish Skills AcquiredAnalyzing, inferring

Teacher’s NotesAfter finishing the three analysisquestions, have students specu-late on what mechanisms allowfish to move successfullybetween fresh water and saltwater. (They should come upwith ideas about osmosis throughthe kidneys and gills.)

Answers to Analysis1. losing ions by excretion2. from fresh water to salt water3. The graph shows that the far-

ther the fish travels, the greaterit’s excreted ion concentration.A fish’s tissues have a lowerconcentration of ions than isfound in salt water, and theylose water through osmosis.One would expect the fish toexcrete more ions as the waterbecomes saltier.

010001011001110101000100100010011100100100010000010100100111010101001000101010010010

Salmon return to spawn in the stream wherethey were hatched. During spawning, femaleslay from 2,000 to 10,000 eggs. The youngsalmon hatch and make their way down-stream to the sea; most perish during thisjourney. A Canadian study reported thatfewer than 1 percent, or approximately 20 to100 hatchlings, of the young from eachfemale survive to spawn. (2,000 � 0.01 � 20,and 10,000 � 0.01 � 100) LogicalLS

MATHMATHCONNECTIONCONNECTION

KidneysVertebrates have a body that is about two-thirds water, and mostwill die if the amount of water in their body falls much lower thanthis. Therefore, minimizing dehydration (water loss) has been a keyevolutionary challenge facing all vertebrates. Even some fishesmust cope with the problem of water loss. If this seems strange toyou, remember that osmosis causes a net movement of waterthrough membranes toward regions of higher ion concentration.

The ion (salt) concentration of sea water is three times that of thetissues of a marine bony fish. As a result, these fishes lose water tothe environment through osmosis. To make up for the water theylose, marine bony fishes drink sea water and actively pump excessions out of their body. Freshwater fishes have the opposite problem.Because their bodies contain more ions than the surroundingwater, they tend to take in water through osmosis. The additionalwater dilutes their body salts, so freshwater fishes regain salts byactively taking them in from their environment.

Although the gills play a major role in maintaining a fish’s salt andwater balance, another key element is a pair of kidneys. Kidneys areorgans made up of thousands of nephrons. are tubelikeunits that regulate the body’s salt and water balance and removemetabolic wastes from the blood. Excess water and bodily wastesleave the kidneys in the form of a fluid called urine. The propertiesof a fish’s urine depend upon the environment in which the fishlives. Marine fishes excrete small amounts of urine while freshwaterfishes excrete large amounts of dilute urine.

Nephrons

Analysis

1. Determine if the fish is losing or gaining ionsby excretion as it travels.

2. Critical Thinking Inferring ConclusionsIs the fish traveling from fresh to salt water orfrom salt to fresh water?

3. Summarize the reasoning you used to answeritem 2.

Analyzing Ion Excretion in FishBackground

A few species of fish, such as adultsalmon, are able to move between salt-water and freshwater environments. Thegraph at right shows the excreted ion con-centration of a fish as it travels from onebody of water to another. Examine thegraph, and answer the analysis questions.

010001011001110101000100100010011100100100010000010100100111010101001000101010010010

www.scilinks.orgTopic: KidneysKeyword: HX4110

Ion Excretion in Fish

Exc

rete

d ion

concentr

ati

on

Distance traveled

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IPC Benchmark Review

To prepare students for the TAKS and accompany the discussion of ion solubility, have students reviewSolubility and Factors That Affect Solubility, TAKS 4IPC 9D on pp. 1054–1055 of the IPC Refresher in theTexas Assessment Appendix of this book.

ReteachingK-W-L Tell students to return totheir lists of things they want toknow about fish, which they createdfor the Bellringer. Have them placecheck marks next to the questionsthat they are now able to answer.Students should finish by making alist of what they have Learned. Ask students:

• Which questions are still unanswered?

• What new questions do you have?

Quiz1. What is the major respiratory

organ of fishes? (gill)

2.What organ eliminates wasteand helps maintain water andsalt balance in fishes? (kidney)

AlternativeAssessmentHave students make two columns ona sheet of paper. Have them labelone column External characteristicsand the other column Internal char-acteristics. Have them review thechapter and list the major internaland external characteristics of fishes.TAKS 2 Bio 8C

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TAKS 2 Bio 10A

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CloseClose

Answers to Section Review

1. Gills allow fish to extract oxygen from the water.Single-loop blood circulation allows blood tobe pumped through the gills and back to theheart. A bony vertebral column surrounds andprotects the spinal cord.

2. Countercurrent flow ensures that oxygen dif-fuses into the blood over the entire length ofthe gill capillaries.

3. The fish heart pumps blood through a single-loop circulatory pathway. The blood goes to thegills and then to the body tissues.

4. Fertilization in sharks is internal; most otherfishes have external fertilization. TAKS 2 Bio 10A; Bio 11A

TAKS 2 Bio 10A;TAKS 3 Bio 7B

TAKS 2 Bio 10A

TAKS 2 Bio 8C

5. Fish A was unable to prevent the inflow ofwater by osmosis when placed in fresh water.Fish B was unable to prevent the outward flowof water by osmosis when placed in salt water.In each case, the resulting imbalance in thefish’s salt concentration caused the fish’s death.

6. A. Incorrect. The atrium is largebut its muscular walls are thin. B. Correct. Theventricle is capable of pumping blood with strongcontractions. C. Incorrect. The sinus venosus is a collection chamber for oxygen-poorblood from the body. D. Incorrect. The conusarteriosus smooths the blood flow and providesonly slightly more force. TAKS 2 Bio 10A

Bio 11A


ReproductionThe sexes are separate in most fishes, and generally fertilizationtakes place externally. In a process called spawning, male and femalegametes are released near one another in the water, as shown inFigure 4. A yolk sac within each egg contains nutrients the develop-ing embryo will need for growth. The yolk sac remains attached tothe hatchling fish but is quickly used up. Then, the growing fish mustseek its own food. More likely than not, it will become food for somelarger animal. Many species of fishes release large numbers of eggsthat are fertilized in a single spawning season. This practice helpsensure that some individuals will survive to maturity.

The eggs of sharks, skates, and rays are fertilized inside thefemale’s body. During mating, the male uses two organs calledclaspers to insert sperm into the female. In most species, the eggsdevelop inside the female and the young are born live. A few speciesof sharks lay eggs.

Real LifeHow many eggs dofemale fish lay duringspawning season? The numberof eggs laid duringspawningvaries fromspecies tospecies.

Some fishes, such assea horses, lay between adozen and several hun-dred eggs. These eggs arewell protected, and mostdevelop into young seahorses. Finding InformationFind out how many eggsare laid by cod.

Figure 4 Fish spawning.These salmon spawn in shallowriver waters. Thousands ofeggs are released in a singlemating, but only a smallpercentage of hatchlings liveuntil adulthood.

Discuss the key characteristics found in all fishes. 8C

Describe how countercurrent flow aids a fish in obtaining oxygen. 10A

Summarize why the fish heart and circulatorysystem are considered important evolutionarychanges. 7B 10A

Contrast reproduction in sharks with that of mostother fishes. 10A 11A

Critical Thinking Forming a HypothesisA student removes Fish A from a saltwater aquarium and Fish B from a freshwater aquarium.By mistake, the student returns each fish to thewrong aquarium. The next day, both fish are dead.Form a hypothesis that explains why.

Which chamber of a fish’sheart generates most of the force that pumps bloodthrough the body? A atrium C sinus venosusB ventricle D conus arteriosus

TAKS Test PrepTAKS Test Prep

Section 1 Review

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Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 7BTAKS Obj 3 Bio 12B TEKS Bio 7B, 8C, 10A, 11A, 12B

Teacher Edition TAKS Obj 2 Bio 8C, 10A TAKS Obj 3 Bio 7B TEKS Bio 7B, 8B, 8C, 10A, 11A

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Section 2

OverviewBefore beginning this sectionreview with your students theobjectives listed in the StudentEdition. This section introducesstudents to the three groups offishes that exist today, and explainshow they differ from each other.

Have students draw a quick pictureof the strangest fish they have everseen (and name it if possible). Tellstudents to list characteristics thatit has in common with all fishes.Then ask them to list characteris-tics that they think are unique tothis fish.

DiscussionProvide students with pictures ofthe following fishes: lamprey, eel,hagfish, hammerhead shark, dog-fish shark, stingray, salmon, trout,and bass. Display the pictures atthe front of the room, and explainthat they are classified into threedistinct groups. Have students tryto determine which fish belong inthe same groups and why. List thecharacteristics students mention assimilar or dissimilar for each fish.(Students may note jaws or lack ofjaws, paired or unpaired fins, scalesor no scales, gill slits or no gill slits,etc.) Discuss how structural charac-teristics are often important inclassifying organisms, and how thefishes are good examples of this.

Visual TAKS 2 Bio 8C; Bio 8BLS

MotivateMotivate

TAKS 2 Bio 8C; Bio 8B

Bellringer

FocusFocus


• Lesson Plan• Directed Reading• Active Reading• Data Sheet for Quick Lab GENERAL

GENERAL

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Chapter Resource File• Reading Organizers• Reading Strategies • Basic Skills Worksheet Mass

and Density

Planner CD-ROM

Transparencies

TT BellringerTT Lateral Line in Bony FishTT External Structures of FishTT Internal Structures of Fish

Jawless FishesPerhaps the most unusual fishes found today are the surviving jawlessfishes, the lampreys and hagfishes. These primitive creatures havechanged little over the past 330 million years. Little is known abouthagfishes, which is not surprising when you consider where theylive—on the ocean floor at depths as great as 1,700 m (about 1 mi).Lampreys are better understood and are found in both salt and freshwater. Interestingly, all species of lampreys must return to fresh waterto reproduce, suggesting that their ancestors lived in fresh water.

Lampreys and hagfishes have scaleless, eel-like bodies with multiple gill slits and unpaired fins. Their skeletons are made ofcartilage, a strong fibrous connective tissue, and both kinds offishes retain their notochord into adulthood. Hagfishes, such as theone shown in Figure 5, are scavengers of dead and dying animals onthe ocean bottom. Because of this behavior, they are sometimescalled the “vultures of the sea.” When threatened, a hagfish can pro-duce huge quantities of slime from its roughly 200 slime glands.Recently, biologists have discovered that hagfishes are far morenumerous than once thought and play a vital role in the ecology ofthe oceans.

Most lampreys, such as the one shown in Figure 5, are parasiticon other living fishes. A lamprey has a suction-cup-like structurearound its mouth that it uses to attach itself to its host. Afterattachment, the lamprey gouges out a wound with its rough tongue,feeding on blood and bits of flesh from the wound.

Today’s Fishes Section 2

Objectives● Distinguish between the

three general categories ofmodern fishes.

● Describe the major external and internal characteristics of the yellow perch.

● Summarize features ofbony fishes.

Key Terms

lateral lineoperculumswim bladderteleost

Hagfish Lamprey

These two modern jawless fishes have changed littleover the past 330 million years.

Figure 5 Hagfish and lamprey

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Teaching TipNatural Selection of BodyShape To look for similarities inbody shape, have students diagramthe profile of several living andnonliving things that move quicklythrough water. Examples youmight provide include a shark, atuna, a bottlenose dolphin, a seal,a submarine, and a torpedo. Allhave the basic shape shown below.Ask students why this shape occursin things that need to move rapidlythrough water. (Direct students tothink about water resistance and theneed to direct movement throughwater using fins.) Visual

Using the Figure In Figure 6 point out how theshark’s teeth are arranged in rowson its jaw, with the newer teethbehind the old ones. Explain that ashark’s teeth and scales are verysimilar in structure and that theteeth probably evolved from scales.Both have an inner pulp cavity thatis covered by a layer of dentine andthen by enamel. The shark’s teethare not embedded in its jaw ashuman teeth are. Rather, they siton top of the jaw and thereforebreak off easily. VisualTAKS 2 Bio 8A, 10A

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MISCONCEPTION ALERT

Fear of Sharks Shark attacks are oftenhighly publicized. This has created a fear ofshark attacks that is often greater than theactual probability of an attack. Bees, wasps,and snakes are responsible for far morefatalities each year. In the United States, theannual risk of death from being struck bylightning is 30 times greater than that froma shark attack. An attack by a shark is alsoless common than such beach-relatedinjuries as spinal damage, dehydration,jellyfish and stingray stings, and sunburn.

Cartilaginous FishesSharks, skates, and rays are cartilaginous (KAHRT’l AJ uh nuhs)fishes. Their skeletons are made of cartilage strengthened by themineral calcium carbonate (the material oyster shells are made of).Calcium carbonate is deposited in the outer layers of cartilage andforms a thin layer that reinforces the cartilage. The result is a verylight but strong skeleton.

The shark’s light, streamlined body allows it to move quicklythrough the water in search of prey. Its skin contains cone-shapedplacoid scales, which give the skin a rough texture. As you can seein Figure 6, the shark’s scales and teeth are quite similar in struc-ture. This is because the teeth are actually modified scales. Theteeth are arranged in 6 to 10 rows along the shark’s jaw. The teethin front are pointed and sharp and are used for biting and cutting.Behind the front teeth, rows of immature teeth are growing. Whena front tooth breaks or is worn down, a replacement tooth movesforward. One shark may use more than 20,000 teeth during its life-time. This system of tooth replacement guarantees that the teethbeing used are always new and sharp.

Two smaller groups of cartilaginous fishes, the skates and rays,have flattened bodies that are well adapted to life on the sea floor.Rays are usually less than 1 m (3.3 ft) long, while skates are typicallysmaller. However, the giant manta ray may be up to 7 m (23 ft) wide.Most species of skates and rays have flattened teeth that are used tocrush their prey, mainly small fishes and invertebrates.

www.scilinks.orgTopic: SharksKeyword: HX4163

Magnification: 5�

Magnification: 1�

Teeth

Scales

Figure 6 Shark scales andteeth. The shark’s skin feelslike sandpaper because it iscovered with toothlike scales.The teeth, which are modifiedscales, are similar in structurebut are much larger.

www.scilinks.orgTopic: Sharks in Texas

WatersKeyword: HXX4011

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Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 12B TEKS Bio 7B, 8C, 10A, 12B

Teacher Edition TAKS Obj 2 Bio 8A, 8C, 10A TAKS Obj 3 Bio 7BTAKS Obj 5 IPC 5A, 5B TEKS Bio 7B, 8A, 8C, 10A, 11B, 11CTEKS IPC 5A, 5B

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Demonstration Obtain a transparent tropical fishcalled a glass catfish, commonlyavailable in pet stores. This fishgives a real-life view of the internalorgans of a bony fish. Have stu-dents view the glass catfish and seewhat internal organs they can iden-tify. Have them study the drawingsof the internal structure of theyellow perch for help in identifying the organs.

Visual

Teaching TipTrain Your Fish Fish have theability to detect pressure changes,such as sound waves, through theirlateral line system, so it is possibleto train a fish to come to the sur-face in response to a sound. Tellstudents who have fish to tap theside of their aquarium very gentlyand in the same manner each timethey feed the fish. After a couple ofweeks, the fish will come to the topto feed whenever the aquarium istapped in this manner. Bio 11B

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did you know?Salmon return to their hatching stream.Pacific salmon find their way to the streamwhere they hatched primarily by the sense ofsmell. Vegetation and minerals in the watergive each stream a unique “flavor.” Youngsalmon imprint on this flavor and can remem-ber it 4 or 5 years later when they return tospawn. All Pacific salmon die shortly afterspawning. Interestingly, when young salmon(smote stage) migrate to the sea, they godownstream backward. TAKS 2 Bio 8C

English Language Learners

ActivityFish and Diet It is a good idea toinclude some fish in one’s diet.Have students go to local grocerystores and record the different typesof fish offered. Remind students tolook for canned and frozen fish aswell as fresh fish. Some studentsmay want to survey local restau-rants to determine what kind offish they offer. Have studentsresearch these fish to determinewhere they were caught or raised;their habitats; their nutrient, vita-min, and mineral contents; and anyother interesting characteristics ofthe fish, such as characteristicbehaviors. Kinesthetic Bio 11CLS

GENERAL

Bony FishesJawless and cartilaginous fishes are not as diverse as bony fishes,which are the most numerous of all the fishes. In addition to astrong, internal skeleton made completely of bone, bony fishes havea series of unique structural adaptations that contribute greatly totheir success.

1. Lateral line system. Bony fishes have a fully developed lateralline system. The , shown in Figure 7, is a sensorysystem that extends along each side of a bony fish’s body. As moving water presses against the fish’s sides, nerve impulsesfrom ciliated sensory cells within the lateral line permit the fish to perceive its position and rate of movement. For example,a trout moving upstream to spawn uses its lateral line system toobtain the sensory information it needs to orient its headupstream.

The lateral line system also enables a fish to detect a motionlessobject by the movement of water deflected by that object. The waythat a fish detects an object with its lateral line and the way that youhear music with your inner ear are quite similar. Both processesshare the same basic mechanism—sensory cells with cilia detectvibrations and send this information to the brain.

lateral line

Lateral Line in Bony Fishes

Lateral line

Lateral linecanal

Sensorycells

NerveOpening toexterior

Figure 7 Lateral line.The lateral line contains sensorycells that help a fish perceive itsposition in the water.

Organizing InformationUse the information on this page and the next four pages to draw a concept map that summarizes the characteristics of bony fishes.On your concept map,include information from Up Close: Yellow Perch.

753

IPC Benchmark Fact

A fish’s lateral line senses other objects in the water by detecting reflected water movements fromnearby objects. These water movements or wavesare an example of a mechanical wave—a wave thatrequires a medium. The energy of the vibration thatsets a wave into motion moves through the mediumas the wave passes through. Vibrating particles passenergy down the line to neighboring particles. Askstudents to identify the medium that perpetuates the waves from an object to the lateral line of a fish. TAKS 5 IPC 5A, 5B


Yellow PerchTeacher’s NotesHave students relate theperch’s external structures toits lifestyle and habitat. Havestudents pay special attentionto the specialized senses andswimming adaptations of thissuccessful fish. Then ask stu-dents to classify each labeledinternal structure of the perchaccording to the followingbody systems: nervous system,circulatory system, reproduc-tive system, digestive system,respiratory system, excretory(urinary) system, muscular sys-tem, and skeletal system.

Discussion1. How does the yellow perch

control roll, pitch, and yawwhen it swims? (The dorsalfins prevent roll, the caudalfin controls pitch, and theanal fin controls yaw.)

2.How would a perch findfood if it were kept in thedark? (It could smell the foodand sense the food’s move-ment with its lateral line.)

TAKS 2 Bio 10A;TAKS 3 Bio 7B

Up Close

Pitch

Roll Yaw

Up CloseYellow Perch

Scientific name: Perca flavescens

Size: About 0.3 m (1 ft) long and up to 2.3 kg (5 lb)

Range: Found in lakes and rivers from the Great Lakes tothe Atlantic coast and as far south as South Carolina

Habitat: Lives concealed among vegetation or submergedtree roots

Diet: Feeds on insect larvae, crustaceans, and other fishes

●

●

●

●

●

External Structures

Fins

▼ Scales

Pectoral fin

▼ Pelvic fin

Anteriordorsal fin

Posteriordorsal fin

Caudal fin

AnusAnal fin

EyeNostril

Lateral line The lateral line is a sense organ

that detects vibrations in water that are caused by

currents or pressure waves. The perch uses this

sensory information to direct its movement as it

swims and to detect objects in its environment,

including predators and prey.

▲ Lateral line

Opercula Movements of the opercula draw water into

the perch’s mouth. The water then moves over the gills,

where oxygen and carbon dioxide are exchanged. Then

the water is forced out through the gill slits.

Fins The caudal fin thrusts

from side to side to propel the

fish forward. The dorsal fins

prevent the perch from rolling

over as it swims, and the anal

fin keeps the fish from veering

sideways. Paired pectoral and

pelvic fins assist the fish in

going up or down through the

water, in turning sharply, and

in stopping quickly.

▲ Operculum

Scales Perch scales are thin, bony disks that grow from

cavities in the skin. Scales grow throughout the life of the

fish. Because a scale grows more rapidly when food is plen-

tiful (in spring and summer) than when food is scarce (in

winter), a scale forms growth rings. Counting the growth

rings can give a good estimate of a perch’s age.

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Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 7B TEKS Bio 7B, 8C, 10A

Teacher Edition TAKS Obj 2 Bio 8C, 10ATAKS Obj 3 Bio 7BTEKS Bio 7B, 8C, 10A, 11A

pp. 754–755

TAKS 2, TAKS 3


Yellow Perch 3. Why are the mouth and

opercula needed for a perchto respire? (Movements ofthe opercula draw water inthrough the open mouth andforce the water over the gills,where oxygen is removedfrom the water.)

4. What would happen to ayellow perch that was miss-ing each body system?(nervous system—it could notmove or sense its environ-ment; circulatory system—itscells could not get oxygenand nutrients or get rid ofwastes; reproductive system—it could not produce off-spring; respiratory system—itcould not obtain oxygen oreliminate carbon dioxide;digestive system—it could notbreak down food; excretory(urinary) system—it could notget rid of nitrogen wastes;muscular system—it couldnot move; skeletal system—itsbody would collapse)

5. What would happen if theswim bladder of a perch wassuddenly unable to absorbmore gas or get rid of gas?(The perch would be unable toachieve neutral buoyancy atdifferent levels in the water. Itwould have to use moreenergy to move up or down in the water.)

6. Why is the number of spermcells produced by the perchso much greater than thenumber of egg cells?(Because of external fertiliza-tion, most sperm cells will notreach the egg cells. A greatnumber is needed to ensurethat each egg is fertilized.)

Up Close

Male

Female

Internal StructuresInternal Structures

Brain The optic lobe receives information from

the eyes, and the olfactory bulbs receive information

from chemical-sensing cells. The cerebrum processes

this and other information. The cerebellum coordinates

muscle activity, and the medulla oblongata controls

the function of many internal organs.

Digestive system The digestive system reflects a basic arrangement

of structures found in all vertebrates. Food enters the mouth and passes

from the esophagus to the stomach. The liver secretes bile, and the pan-

creas secretes enzymes into a short intestine. The bile and enzymes help

break down the food. Absorption of digested food occurs through the

inner lining of the intestine. Undigested material exits through the anus.

Reproductive organs Yellow perch produce

gametes during their breeding season in the spring.

The female lays strings of eggs that are fertilized

externally. In warm water, the young hatch within

days and grow quickly. In cold water, the develop-

ment of the eggs may take much longer.

Gallbladder

Heart

Gills

Tongue

▲ Brain

KidneySpinal cord

Vertebra

Swim bladder

Liver

Jaws

Muscle

▼ Stomach ▼ Esophagus▼ Intestine

Anus

Optic lobe

Cerebrum

Olfactory bulbMedulla

oblongata

Spinal cordCerebellumFemale

OvaryOviduct

Vas deferensBladder

TestisMale

Kidney

▲ Reproductive organs

755

did you know?Swim bladders can be damaged. Swimbladders on some fish have been known toleak or rupture, releasing the gas into the bodycavity. In some instances, the fish floats to thetop of the water, causing it to be easy prey forhungry predators. Only by frenzied swimmingcan the fish manage to stay under water, and itwill soon tire and return to float on the top.Ask students to imagine trying to dive underwater while holding a large balloon.

Intrapersonal TAKS 2 Bio 8C; Bio 11ALS


(continued)4. It would take a great deal of energy to stay in

one position under water with two lungs full of air. A swim bladder offers a fishtremendous savings of energy because the fish controls the amount of gas in the swimbladder. This makes more energy available for daily activities, such as catching prey orescaping predators.


Modeling theAction of a SwimBladderSkills AcquiredObserving, analyzing,applying knowledge

Teacher’s Notes Have all students drop theirraisins into the soft drink at thesame time.

Answers to Analysis1. The raisins sank to the bottom.

As bubbles collected on themthey rose to the top, then theysank again.

2. The bubbles clung to theraisins and imparted buoyancy,causing the raisins to rise.When the raisins reached thetop, the bubbles burst, and theraisins sank again.

3. The bubbles formed on theoutside of the raisin. A swimbladder is internal. Also, theamount of gas in the swimbladder can be increased ordecreased, unlike the bubbleson the raisins.

2. Gill cover. Most bony fishes have a hard plate, an ,that covers the gills on each side of the head. Movements of cer-tain muscles and of the opercula, shown in Figure 8, permit abony fish to draw water over the gills, which enables the fish totake in oxygen. By using this mechanism, most bony fishes canmove water over their gills while remaining stationary in thewater. A bony fish doesn’t have to swim forward with its mouthopen to move water over its gills. This ability to respire withoutswimming enables a bony fish to conserve energy that can bespent chasing after prey and escaping from predators.

3. Swim bladder. The density of the fish body is slightly greaterthan that of sea water. How then do bony fishes keep from sinking?Bony fishes contain a special gas sac called a . Byadjusting the gas content of the swim bladder, bony fishes canregulate their buoyancy. As the swim bladder fills, the fish rises,and as it empties, the fish sinks. The swim bladder of early bonyfishes was connected to their throat, and they gulped air to fill it.The swim bladder of modern bony fishes, shown on the previouspage, does not have a direct passage to the mouth. Instead, gas isexchanged between the bloodstream and the swim bladder. Thispermits the fish to maintain or change its depth in the water.

There are two groups of bony fishes, the ray-finned fishes and thelobe-finned fishes. The yellow perch described in Up Close: YellowPerch on the previous two pages is a common type of ray-finned fish.

swim bladder

operculum

Water

Water

Operculumclosed

Operculumopen

Figure 8 Operculum.When a fish’s mouth opens,water enters and the operculaclose over the gills. When themouth closes, the operculaopen and water moves acrossthe gills and out of the fish.

Modeling the Action of a Swim BladderMost fish use a swim bladder to regulate theirdepth in water. As gas enters the swim bladder, thefish rises in the water. As gas is expelled, the fishsinks to a lower depth.

Materials

100 mL beaker or small glass; cold, clear, carbonated soft drink; 2 very dry raisins

Procedure

1. Fill a 100 mL beaker with acold, carbonated soft drink.

2. Drop two raisins into thebeaker, and observe whathappens over the next 5 minutes.

Analysis

1. Describe what happenedafter you dropped the raisinsinto the soft drink.

2. Forming HypothesesDevelop a hypothesis toexplain your observations.

3. Critical ThinkingAnalyzing Results Howdoes the lifting of the raisinsdiffer from the use of a swimbladder to control buoyancy?

4. Critical Thinking Form-ing Reasoned OpinionsThink about the energy youwould have to expend tokeep yourself in one positionunder water. What advantagemight a swim bladder provideto a fish?

2A 2C 3E

756

TAKS 1 Bio/IPC 2A, 2C; Bio 3E

Student Edition TAKS Obj 1 Bio/IPC 2A, 2CTAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B (grade 11)TAKS Obj 3 Bio 12B TEKS Bio 3E, 10A, 10B, 12BTEKS Bio/IPC 2A, 2C

Teacher Edition TAKS Obj 1 Bio/IPC 2A, 2C TAKS Obj 2 Bio 8C, 10A, 10B TAKS Obj 3 Bio 7B, 12B TAKS Obj 4 IPC 7ATEKS Bio 3E, 7B, 8C, 10A, 10B,11A, 11B, 12BTEKS Bio/IPC 2A, 2CTEKS IPC 7A

pp. 756–757IPC Benchmark Fact

Remind students that buoyancy increases as the den-sity of an object decreases. Ask them what happensto a fish’s average density and therefore its buoyancywhen the swim bladder increases or decreases insize. Also, ask students whether a fish’s swim bladdershould increase of decrease in size if a fish wants toswim in deeper water. TAKS 4 IPC 7A (grade 11 only)

TAKS 1


1. Agnathans: jawless, scaleless, have unpaired fins.Cartilaginous fishes: cartilaginous skeletons,streamlined bodies, placoid scales. Bony fishes:bony skeletons, opercula, swim bladders, well-developed lateral line system.

2. The operculum pumps water through the mouthand over the gills for oxygen extraction.

3. A fish can maintain a particular depth in thewater by adjusting the amount of gas in thebladder rather than by using muscular force.

4. Food enters the mouth and moves to the stom-ach. Substances in the intestine help break

TAKS 2 Bio 10A

TAKS 2 Bio 10A

TAKS 2 Bio 8C

down food. Nutrients are absorbed in theintestine and undigested food exits the bodythrough the anus.

5. Both have sensory cells that sense vibrations andsend nerve impulses to the brain.

6. Disagree; these are characteristics of cartilagi-nous fishes, which have no swim bladder.

7. A. Incorrect. Whales have comb-like teeth for straining plankton. B. Incorrect. Seeanswer D. C. Incorrect. Hagfishes have mouthsadapted to eating dead animals. D. Correct. Thelamprey’s mouth is like a suction-cup to attachitself to its host. TAKS 3 Bio 7B; Bio 12B

TAKS 2 Bio 8C, 10A, 10B (grade 11 only)

TAKS 2 Bio 8C, 10A

TAKS 2 Bio 8C, 10A

ReteachingHave students work in smallgroups to make a table that com-pares each type of fish they havestudied in this section. Across thetop of their table they should writeJawless Fish, Cartilaginous Fish,and Bony Fish. The titles of therows down the side of the table willvary from group to group. Havegroups fill in the table with infor-mation they have learned. Eachgroup can then present its table tothe class. Have individual studentscopy his or her group’s table andplace it in his or her portfolio.

Quiz1. How are the skeletons of sharks,

skates, and rays similar to thoseof jawless fishes? (Both groups of fishes have skeletons made ofcartilage.)

2.What are teleosts and how com-mon are they? (Teleosts are ray-finned bony fishes with highlymobile fins, thin scales, and sym-metrical tails. They represent 95%of all living fish species.)

AlternativeAssessmentAfter reviewing the section, haveeach student choose a favorite fish.Have them give a short oral report,explaining to the class how theparticular characteristics of theirchosen fish enable it to survive andgive it an advantage over othertypes of fish. Have each studentwrite the name and category oftheir fish on the board prior totheir presentation and provide apicture or illustration of the fishfor class viewing. Bio 11B, 12B

GENERAL

TAKS 2 Bio 8C

GENERAL

CloseClose


Figure 10 Coelacanth.Coelacanths were thought tohave been extinct for millionsof years, until one was caughtoff the coast of Africa in 1938.Coelacanths can reach up tonearly 3 m (9.8 ft) in length.

Ray-Finned Bony FishesRay-finned bony fishes, such as the ones shown in Figure 9,comprise the vast majority of living fishes. Their fins are supportedby bony structures called rays. (TEL ee ahsts), such as theyellow perch you saw in Up Close, are the most advanced of the ray-finned bony fishes. Teleosts have highly mobile fins, very thinscales, and completely symmetrical tails. About 95 percent of all liv-ing fish species are teleosts.

Lobe-Finned Bony FishesOnly seven species of lobe-finned fishes survive today. One species isthe coelacanth (SEE luh kanth), shown in Figure 10, and the other sixspecies are all lungfishes. The lobe-finned fishes have paired fins thatare structurally very different from the fins of ray-finned fishes. Inmany lobe-finned fishes, each fin consists of a long, fleshy, muscularlobe that is supported by a central core of bones. These bones are con-nected by joints, like the joints between the bones in your hand. Bonyrays are found only at the tips of each lobed fin. Muscles within eachlobe can move the bony rays independently of each other.

Scientists have debated whether the direct ancestor of amphibianswas a coelacanth or a lungfish. However, recent evidence has led biol-ogists to believe that it was neither. The ancestor of the amphibiansmost likely was a third type of lobe-finned fish that is now extinct.

Teleosts

Section 2 Review

Compare the three categories of modern fishes.

Summarize the role of the operculum in fishrespiration. 10A

Summarize how the swim bladder can beviewed as an energy-saving mechanism. 10A

Describe the digestive process in a yellowperch. 8C 10A

Relate a yellow perch’s lateral line system to the human ear. 8C 10A

Critical Thinking Evaluating ConclusionsAn unidentified species of fish has rough skin,several rows of teeth, and no opercula. Based onthese characteristics, a student infers that thefish has a swim bladder. Explain why you agreeor disagree with this conclusion. 8C 10A 10B

The mouth of a lamprey isspecialized for A straining plankton.B chewing seaweed.C scavenging dead animals.D parasitizing other fish.

TAKS Test PrepTAKS Test Prep7B 12B

At sexual maturity, Pacificbluefin tuna can weigh about136 kg (300 lb), althoughsome grow larger.

Figure 9 Pacific bluefin tuna

8C

757

OverviewBefore beginning this sectionreview with your students theobjectives listed in the StudentEdition. This section introducesstudents to how amphibians differfrom fish and discusses the adapta-tions amphibians have for life inand out of water.

Tell students to think about howbig the largest frog species gets.Then ask them to list some thingsthat a frog that size would eat. (Thelargest frog species is Gigantoranagoliath of West Africa. It can be morethan 30 cm (1 ft) long and can weighover 3.3 kg (7.5 lb). It eats other ani-mals as large as rats and ducks.

ActivityExplain that a caecilian is a legless,wormlike animal. Ask students toclose their books, and write thewords Apoda, Anura, and Urodelaat the top of three columns on theboard. Tell students that theseorder names come from the Greeklanguage. To the side write a—“without,” oura—“tail,” pous—“foot,” and delos—“visible.” Askstudents to place the followingamphibians into the propercolumns by thinking of each ani-mal’s characteristics and what thethree column headings mean: toad,salamander, bullfrog, caecilian,newt, and tree frog. (Apoda—caecilian; Anura—toad, bullfrog, andtree frog; Urodela—salamander andnewt) Verbal TAKS 2 Bio 8C; Bio 8BLS

GENERAL

MotivateMotivate

Bellringer

FocusFocus

Section 3


• Lesson Plan• Directed Reading• Active Reading GENERAL

GENERAL

Chapter Resource File

• Reading Organizers• Reading Strategies • Supplemental Reading Guide

Through a Window

Planner CD-ROM

Transparencies

TT BellringerTT Fish and Amphibian CirculationTT Amphibian Heart StructureTT Life Cycle of a FrogTT External Structure of a FrogTT Internal Structure of a Frog

Section 3 Amphibians

Key Characteristics of Modern AmphibiansThe next time you see a frog, consider that it is a surviving memberof an ancient amphibian group, the first vertebrates to walk onland. The croaking and peeping of frogs, such as the one shown inFigure 11, make it difficult not to notice them, but their smaller, qui-eter relatives live nearby, hidden in damp habitats. Class Amphibiacontains three orders of living amphibians: order Anura (frogs andtoads), order Urodela (salamanders and newts), and order Apoda(caecilians). Most amphibians share five key characteristics.

1. Legs. The evolution of legs was an important adaptation for liv-ing on land. Frogs, toads, salamanders, and newts have four legs.Caecilians lost their legs during the evolutionary course ofadapting to a burrowing existence.

2. Lungs. Although larval amphibians have gills, most adultamphibians breathe with a pair of lungs. Lungless salamandersare an exception.

3. Double-loop circulation. Two large veins called pulmonaryveins return oxygen-rich blood from the lungs to the heart. Theblood is then pumped to the tissues at a much higher pressurethan in the fish heart.

4. Partially divided heart. The atrium of the amphibian heart isdivided into left and right sides, but the ventricle is not. A mix-ture of oxygen-rich and oxygen-poor blood is delivered to theamphibian’s body tissues.

5. Cutaneous respiration. Most amphibians supplement theiroxygen intake by respiring directly through their moist skin.Cutaneous respiration (“skin breathing”) limits the maximumbody size of amphibians because it is efficient only when thereis a high ratio of skin surface area to body volume.

LungsAlthough air contains about 20 times as much oxygen as sea waterdoes, gills cannot function as respiratory organs when out of water. Thus, one of the major challenges that faced the first landvertebrates was that of obtaining oxygen from air. The evolutionarysolution to this challenge was the lung.

A is an internal, baglike respiratory organ that allows oxy-gen and carbon dioxide to be exchanged between the air and thebloodstream. The amount of oxygen a lung can absorb depends onits internal surface area. The greater the surface area, the greaterthe amount of oxygen that can be absorbed. In amphibians, the

lung

Objectives● Summarize the

characteristics of modernamphibians.

● Compare the three orders ofliving amphibians.

● Describe the major externaland internal characteristicsof the leopard frog.

Key Terms

lungpulmonary veinseptum

Figure 11 Spring peeper.In some areas, the call of thespring peeper is one of the firstsigns of spring.

7B 8C

8B 8C

10A

758

Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 7B TEKS Bio 7B, 8B, 8C, 10A

Teacher Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TEKS Bio 3E, 8B, 8C, 10A, 12C

pp. 758–759

TAKS 3

TAKS 2

TAKS 2

Reading Organizer Have stu-dents create a Venn diagramsimilar to the one shown in theGraphic Organizer at the bottomof this page. As students readSection 3, have them list, in theappropriate regions of the diagram,the characteristics that areexclusive to fish, exclusive toamphibians, and common to bothgroups. After the diagram is com-plete, have each student use theinformation in the diagram towrite a paragraph that either sup-ports or rejects the placement offish and amphibians into twoseparate groups. Logical

Teaching TipGas Exchange Tell students thatalthough most amphibians havelungs, some species of salamandersexchange oxygen and carbon diox-ide through gills, even as adults.Ask students where they wouldexpect to find these amphibiansand why. (in an aquatic environ-ment; because gills collapse in air)Tell students that many species ofsalamanders have neither lungs norgills and respire entirely throughtheir skin. Verbal

Using the FigureUse Figure 13 to compare the cir-culatory pathways of fish andamphibians. Ask: Which system isa single loop and which is a doubleloop? (The fish system is a singleloop, and the amphibian system is adouble loop.) What is the functionof the second loop in the amphib-ian system? (The second loop createsa circulatory pathway to and fromthe lungs.) What advantage doesthe double-loop system provide?(The amphibian’s heart pumpsoxygen-rich blood to the amphibian’stissues at much higher pressures thancan happen in the fish’s single-loopsystem.) Visual TAKS 2 Bio 10ALS

TAKS 2 Bio 8C; Bio 12CLS

Bio 8B; Bio 3ELS

GENERALBUILDERSKILL

TeachTeach


Graphic Organizer

Amphibian characteristics

exclusive characteristics

Fish characteristics

exclusive characteristics

commoncharacteristics

Use this graphic organizer with the Skill Builder on this page.

Gill capillaries

Body organcapillaries

Heart Heart

Pulmonary vein

Oxygen-richblood

Oxygen-poorblood

Lung capillaries

Fish Amphibian

Circulation in fishes involves a single loop. Amphibians have a second loop thatgoes from the heart to the lungs and back to the heart.

Figure 13 Circulatory loops

lungs are hardly more than sacs with folds on their innermembrane that increase their surface area, as shown in Figure 12. With each breath, fresh oxygen-rich air is drawninto the lungs. There it mixes with a small volume of airthat has already given up most of its oxygen. Because ofthis mixing, the respiratory efficiency of lungs is much lessthan that of gills. Because there is much more oxygen inair than there is in water, however, lungs do nothave to be as efficient as gills. Many amphib-ians also obtain oxygen through their thin,moist skin.

Double-Loop CirculationAs amphibians evolved and became active onland, their circulatory system changed, result-ing in a second circulatory loop. This changeallowed more oxygen to be delivered to theirmuscles. Figure 13 compares the single-loop circulation of mostfishes with the double-loop circulation of amphibians (also foundin lungfishes). Notice that amphibians have a pair of blood vesselsnot found in fishes, the pulmonary veins. The carry oxygen-rich blood from the amphibian’s lungs to its heart.The heart pumps the oxygen-rich blood to the rest of the body. The advantage of this arrangement is that oxygen-rich blood can bepumped to the amphibian’s tissues at a much higher pressure thanit can in fishes. (Recall that in fish, blood is pumped through thegills before reaching the body organs. As a result, much of the forceof the heartbeat is lost.)

pulmonary veins

Figure 12 Amphibianlungs. The lungs of anamphibian are sacs with afolded internal membrane thatprovides a large surface forgas exchange.

759

Teaching TipComparing Heart AnatomyHave students compare the heart ofthe amphibian in Figure 14 with thatof the fish in Figure 3. Ask them tolist the similarities and differencesbetween the two. Then have eachstudent compare his or her list withthat of a partner.

Visual

Demonstration To illustrate that oxygen-rich andoxygen-poor blood tends to stayseparate in the amphibian’s ventri-cle, show how two liquids with different densities tend to separate.Fill a graduated cylinder about halffull with corn syrup. Ask studentswhat they think will happen if youadd colored water to the cylinder.(The clear corn syrup will remain atthe bottom.) Then fill the rest of thecylinder with colored water. In asecond cylinder, reverse the orderin which you add the liquids. Askstudents to predict what will hap-pen when you add the corn syrupto the colored water. (The syrupwill sink to the bottom.) Visual

Using the Figure Have students closely examineFigure 14. Tell them that the heart shown in the frog is drawn indorsal view, with the blue sinusvenosus on top. Explain that theheart shown in the enlargement isdrawn in ventral view. The sinusvenosus is not visible in theenlargement, but the three blueveins that carry blood to the sinusvenosus are visible. VisualTAKS 2 Bio 8C, 10A

LS

GENERAL

LS

GENERAL

LS

GENERAL



MISCONCEPTION ALERT

Do toads cause warts? Some studentsmay have the false idea that they can getwarts from toads. Explain that this is nottrue. Warts are caused by viruses that arenot carried on toads. The rough, “warty”appearance of the toad’s skin is an adapta-tion for living successfully in dry habitatsand is not due to skin problems.


www.scilinks.orgTopic: Circulation in

AmphibiansKeyword: HX4043

Circulation of BloodNot only did the path of circulation in amphibians change, but several important changes occurred in the heart. As you read aboutthese changes, use Figure 14 to trace the flow of blood through theamphibian heart.

The sinus venosus continues to deliver oxygen-poor blood fromthe body to the right side of the heart, as shown in step 1. (You cansee the sinus venosus on the left side of Figure 14.) In addition, oxygen-rich blood from the lungs enters the left side of the heartdirectly, as shown in step 2.

A dividing wall known as the separates the amphibianatrium into right and left halves. You cannot see the septum in Figure 14 as it is beneath the conus arteriosus. The septum preventsthe complete mixing of oxygen-rich and oxygen-poor blood as eachenters the heart. As shown in step 3, both types of blood empty intoa single ventricle, where some mixing of oxygen-rich and oxygen-poor blood occurs. However, due to the anatomy of the ventricle,the two streams of blood remain somewhat separate, as shown instep 4. Oxygen-rich blood tends to stay on the side that directsblood toward the body. Oxygen-poor blood tends to stay on the sidethat directs blood toward the lungs.

A number of amphibians have a spiral valve that divides theconus arteriosus. The spiral valve also helps to keep the two streamsof blood separate as they leave the heart. Even so, some oxygen-poor blood is delivered to the body’s tissues. Recall, however, thatamphibians also obtain oxygen through their skin. This additionaloxygen partly offsets the limitations of their circulatory system.

septum

Amphibian Heart Structure

LeftatriumRight

atrium

Conusarteriosis

Pulmonaryvein

Pulmonaryvein

Frombody

Fromlungs

From body

To bodyTo lungs

Ventricle

The pulmonary veinscarry oxygen-rich

blood from the lungs to theleft atrium.

2

A mixture of oxygen-rich and oxygen-poor

blood enters the ventricle.

3

The ventricle pumpsblood to the lungs

and the body tissues.

4

Oxygen-poor blood from the body enters

the right atrium.

1

Sinusvenosus

Figure 14 Amphibianheart. These four steps showhow blood flows through theheart of an amphibian.

760

Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 7B TEKS Bio 7B, 8C, 10A

Teacher Edition TAKS Obj 2 Bio 8C, 10A TAKS Obj 4 IPC 9D TEKS Bio 8C, 10A, 11B, 12C, 12DTEKS IPC 9D

pp. 760–761

IPC Benchmark Fact

Fish gills and amphibian lungs have large surfaceareas for gas exchange which increases the amountof oxygen absorbed. Other factors, such as stirring orshaking and usually heating, also increase the rate at which a solute dissolves in a solvent. However,remind students that even though the rate at which asolute dissolves varies, a solute’s solubility is con-stant at a given temperature.TAKS 4 IPC 9D (grade 11 only)

Teaching TipTadpole MetamorphosisPurchase some “hind limb bud-stage” tadpoles from a biologicalsupply company. Keep the tadpoles in a small, aerated aquarium, and have studentsmake written or drawn observa-tions every few days. Students willnote that the tail gets shorter, thebody gets squarer, and the hindlimb buds develop into hind legs.Some tadpoles also may begin todevelop front legs, but the mortal-ity rate at this stage is high. Pointout that while these dramaticexternal changes are taking place,important internal changes areoccurring as well. In most species,the tadpole’s digestive systemchanges to accommodate theswitch from an herbivorous to acarnivorous diet. The respiratorysystem changes from gills to lung-and-skin respiration in the adultfrog. If neither plant nor animalfood is available to the metamor-phosing tadpole at the precisetime, it can starve. Likewise, if thetadpole does not have a place torest its head above water, it candrown as its respiratory system changes.

Visual

Using the Figure Have students examine Figure 16.Have them note the externalchanges that are taking place in thefrog. Then ask students to hypoth-esize about what internal changesare also occurring. Have themthink about the different lifestylesof a frog and a tadpole. (digestivesystem—herbivore to carnivore; res-piratory system—gills to lungs)

Visual Bio 8CLS

GENERAL

Bio 11B, 12DLS


did you know?Some frogs have developed amazing waysto prevent their eggs from drying out.The female Surinam toad (actually a frog) ofSouth America carries her eggs in pockets ofskin on her back. As many as 60 young passthrough the tadpole stage while imbedded inher back and then emerge as small frogs.Another species of frog in Australia swallowsthe eggs and keeps them in the stomach untilthe young emerge out of the adult’s mouth.Bio 11B, 12C


StrategiesStrategiesINCLUSIONINCLUSION

Have students create a poster showing thedifferences between frogs and toads. Theposter should compare and contrast the char-acteristics of these amphibians, describing theindividual characteristics of the frog and thetoad, as well as the similarities or differencesof how and where these two amphibians live.The poster should have drawings or picturesof different frogs and toads.

• Developmental Delay• Learning Disability

• Attention DeficitDisorder

Frogs and ToadsThe order Anura is made up of frogs and toads that live in envi-ronments ranging from deserts to rain forests, valleys to moun-tains, and ponds to puddles. Adult anurans are carnivorous, eatinga wide variety of small prey. Some species have a sticky tongue thatthey extend rapidly to catch their prey. The frog body, particularlyits skeleton, is adapted for jumping, and its long muscular legsprovide the power. To learn about the leopard frog, see Up Close:Leopard Frog on the next two pages. Toads, such as the one shownin Figure 15, are very similar to frogs but have squat bodies andshorter legs. Their skin is not smooth like that of a frog but iscovered with bumps.

Reproduction in FrogsLike most living amphibians, frogs depend on the presence of waterto complete their life cycle. The female releases her eggs into thewater and a male’s sperm fertilize them externally. After a few days,the fertilized eggs hatch into swimming, fishlike larval forms calledtadpoles. Tadpoles breathe with gills and feed mostly on algae. Aftera period of growth, the body of the tadpole changes into that of anadult frog. The rate at which tadpoles develop depends on thespecies and the availability of food. This process of dramatic physicalchange, called metamorphosis, is shown in Figure 16.

Youngfrog

Front legsappear

Hind legsappear

Hatchlingtadpole

Fertilizedeggs

Adult

The transition of a larval frog (tadpole) to an adult involves a complex series ofexternal and internal body changes.

Figure 16 Frog life cycle

Figure 15 Toad. Toads likethis common Asian toad havedry, bumpy skin and relativelyshort legs.

761


Leopard Frog

Teacher’s Notes • Have pairs of students make

two columns on a sheet ofpaper. Ask them to label oneWater and the other Land.As students read about theleopard frog, have them putthe characteristics of the froginto one or both of thecolumns, depending on thenature of each characteristic.For example, Tympanicmembrane would go in bothcolumns, while Webbed toeswould go under Water. Leada discussion in which con-flicting results are analyzed.

• Have students compare theorgan systems of the frog withthose of the yellow perch.Have them describe the simi-larities and differences.

DiscussionGuide discussion by posing thefollowing questions:

1. How do you think the leop-ard frog got its name? (itsspotted appearance)

2.How is the ear of the frogsimilar to the lateral line ofthe yellow perch? (Bothstructures contain ciliated sen-sory cells.)

3. Why do frogs produce somany eggs and sperm?(Their eggs and larvae areeaten by many predators.)

4. How do leopard frogsbreathe? (with lungs andthrough their skin)

Up Close

did you know?A frog’s ears are external. Most frogs andtoads have a tympanic membrane on the sur-face of both sides of their head. The tympanicmembranes of a human are called eardrums,and each is protected inside the ear canal.TAKS 2 Bio 10A

Up CloseLeopard Frog

Scientific name: Rana pipiens

Size: Body length (legs excluded) of 5–9 cm (2–3.5 in.)

Range: From northern Canada to southern New Mexico andfrom eastern California to the Atlantic coast

Habitat: Lives in the short grass of meadows and aroundponds

Diet: Feeds on crickets, mosquitoes, and other small animals

●

●

●

●

●

External Structures

Eye Because its eyes bulge out from its

head, the leopard frog can stay almost

fully submerged while literally “keeping

an eye out” for predators above the

water. Its eyes work equally well in or out

of water. Eyelids that blink protect the

eyes from dust. In addition, a transparent

membrane covers each eyeball, keeping

it moist and protecting it when the frog

is underwater.

Skin Mucous glands embed-

ded within the skin supply a

lubricant that keeps the skin

moist, a necessity for respira-

tion. Unlike those of many

frogs and toads, the leopard

frog’s skin glands do not

secrete poisonous or foul-

tasting substances. Instead,

the leopard frog must rely on

its protective coloration and

speed to evade predators.

Tympanic membraneWhen sound causes the tym-

panic membrane (eardrum) to

vibrate, a tiny bone transmits

the vibrations to the inner ear.

There, ciliated sensory cells

(similar to those found in the

lateral line of a fish) detect the

vibrations and help the frog

maintain balance. Leopard

frogs hear well in both water

and air.

Tympanic membrane

▼ Eye

Foreleg

Webbed toe

Jumping leg

▼ Skin

▼

762

TAKS 2, TAKS 3

TAKS 2 Bio 8C, 10A; TAKS 3 Bio 12B

Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 12B TEKS Bio 8C, 10A, 12B

Teacher Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 12B TEKS Bio 8C, 10A, 12B, 12C

pp. 762–763


Leopard Frog 5.Why is a fish more agile

in the water than a frog? (A more-developed cerebel-lum in the fish enables it tohave better muscle coordina-tion. Also, a fish’s streamlinedbody and fins are modifica-tions for movement throughwater.)

6.Why will a fish suffocate if it is taken out of water?(Its gills will collapse, dryout, and no longer absorboxygen.)

7.How does a frog change itsdepth in water? (It swimsusing its webbed feet.)

8.Why is it vital for malefrogs to call to females?(Frogs are camouflaged andmay not find each other bysight alone. Each species offrog has its own mating call,which prevents females frommating with the wrongspecies of male.)

9.What is the advantage of a frog of having its eyes onthe top of its head? (Inwater, the frog can keep mostof its body hidden from pred-ators while still being able towatch for them or for prey.)

10.How can a frog stay under-water for so long with suchsmall lungs? (It can alsoabsorb oxygen through itsskin.)

Up CloseInternal Structures

Brain

Esophagus

▼

▼

Cloaca Undigested material passesinto the cloaca, a chamber that opensto the outside of the body. Urine fromthe kidneys travels to the bladder andthen passes into the cloaca, as dogametes from the reproductive organs.All of these materials exit the bodythrough the cloacal opening.

Tongue and jaw The tongue flicks out with

great speed, curls around the prey, and returns

to the mouth. Two large teeth that project from

the roof of the mouth impale struggling prey.

In addition the upper jaw is lined with small,

sharp teeth that prevent the prey from escap-

ing. Food is not chewed but swallowed whole.

▼ Reproductive organs

Intestine Stomach Liver

HeartLung

Teeth

Reproductive organs Prior to breed-

ing, the reproductive organs of male and

female leopard frogs produce enormous

numbers of gametes. The female releases

a large cluster of eggs into the water.

The male then discharges his sperm

over them, fertilizing them externally.

Optic lobeCerebellum

Cerebrum

Medulla oblongataOlfactory lobe

Skeleton The skeletal system of

the leopard frog (and all other mod-

ern frogs) has only nine vertebrae

and no ribs. The rest of the verte-

brae are fused into a single bone

(urostyle). When a frog is sitting, the

urostyle points upward, which gives

the frog its characteristic humped

back. When a frog jumps the long

hind legs extend, which produces

a powerful thrust forward.

▼ Cloaca

Urinary bladder

Urostyle

Sacralvertabra

Kidney

Tongue

Pelvic girdle

▼

FemaleMaleMature ovary

Oviduct

Ureter

Kidney

Cloaca

Testis

Brain The frog’s brain differs from the

fish’s brain in that its components are

more complex. For example, the larger,

more complex cerebrum of a frog is able

to process a wider assortment of sen-

sory information than the cerebrum of

a fish can.

763

ReteachingHave students make a list of charac-teristics that distinguish amphibiansfrom fish. (Answers might includethat amphibians have legs and lungs,can live on land, exchange gasesthrough their skin, and have a double-loop circulatory system.)

Quiz1. What is the main respiratory

organ of most adult amphibians?(lungs)

2.What are two important waysthat most amphibians depend onthe presence of water? (forreproduction and for cutaneousrespiration)

3. How are toads different fromfrogs? (Toads have squat bodieswith shorter legs and their skin isdry and bumpy to prevent waterloss in drier environments; frogsare have moist skin and longerbodies and legs.)

AlternativeAssessmentHave students work in groups toprepare a poster showing the frog’slife cycle. The poster shouldinclude drawings of each of thefour stages of a frog’s life. Next toeach drawing, students should adda paragraph that explains what isillustrated by the drawing andwhat they have learned about it.For example, next to the drawingof frog eggs, the paragraph couldexplain how frog eggs are fertilizedand where they are laid.

GENERAL

TAKS 2 Bio 8C, 10A; Bio 8B

GENERAL

CloseClose


1. through gills, lungs, or skin2. In single-loop circulation, blood is pumped

through gills and then travels through the body.In double-loop circulation, blood is pumped tothe lungs and then travels back to the heart,which pumps it to the rest of the body.

3. Apoda—small bony scales embedded in theskin, legless; Urodela—elongated bodies withtails; Anura—elongated hind legs and no tail

4. Except for a few species of salamanders, bothhave external fertilization. Tadpoles undergo aradical metamorphosis to become frogs; larval

TAKS 2 Bio 10A; Bio 8B

TAKS 2 Bio 10A; TAKS 3 Bio 7B

TAKS 2 Bio 10A salamanders resemble adults with gills.

5. The tongue can be flicked out at great speed tocapture prey.

6. Bulging eyes give a wide field of vision. Largetympanic membranes readily detect sounds.

7. A. Correct. The left atriumreceives oxygen-rich blood from the lungs.B. Incorrect. Oxygen-poor blood from thebody is received in the right atrium.C. Incorrect. From the left atrium, blood goesto the ventricle. D. Incorrect. Blood goes to theventricle from the left atrium. TAKS 2 Bio 10A

TAKS 2 Bio 10A

TAKS 3 Bio 7B, 12B

TAKS 2 Bio 10A; Bio 8B


Salamanders and CaeciliansSalamanders have elongated bodies, long tails, and smooth, moistskin. There are about 369 species of salamanders, all belonging tothe order Urodela. They typically range from 10 cm to 0.3 m (4 in.to 1 ft) in length. However, giant Asiatic salamanders of the genusAndrias grow as long as 1.5 m (5 ft) and weigh up to 41 kg (90 lb).Because salamanders need to keep their skin moist, most are unableto remain away from water for long periods, although some sala-mander species manage to live in dry areas by remaining inactiveduring the day.

Salamanders lay their eggs in water or in moist places,as shown in Figure 17. Fertilization is usually external. Afew species of salamanders practice a type of internalfertilization in which the female picks up a sperm packetthat has been deposited by the male and places it in hercloaca. Unlike frog and toad larvae, salamander larvaedo not undergo a dramatic metamorphosis. The youngthat hatch from salamander eggs are carnivorous andresemble small versions of the adults, except that theyoung usually have gills. A few species of salamanders,such as the North American mudpuppy and the Texasspring salamander, never lose their larval characteristics.They retain their external gills as adults.

CaeciliansCaecilians (order Apoda) are a highly specialized groupof tropical, burrowing amphibians with small, bonyscales embedded in their skin. They feed on small inver-tebrates found in soil. These legless, wormlike animals,shown in Figure 18, grow to about 0.3 m (1 ft) long,although some species can be up to 1.2 m (4 ft) long.

During breeding, the male deposits sperm directly into the female.Depending on the species, the female may bear live young or layeggs that develop externally. Caecilians are rarely seen, and scien-tists do not know a lot about their behavior.

Figure 17 Salamander.This four-toed salamander hasdeposited its eggs in a damp,mossy environment.

Figure 18 Caecilian. Likemost caecilians, this one fromColombia, South America,burrows beneath the soil andis rarely seen.

Summarize how amphibians take in oxygen.

Contrast the single-loop circulation of fish withthe double-loop circulation of amphibians.

Compare the external characteristics of eachorder of amphibians. 8B 8C

Compare reproduction and development infrogs and salamanders. 8B 10A

Relate the tongue of the leopard frog to its feeding habits. 7B 12B

Explain why it is difficult to “sneak up” on a frog. 10A

In a frog’s heart, the bloodthat enters the left atrium A comes from the lungs. C then goes to the lungs.B comes from the body. D then goes to the body.


Section 3 Review

10A

10A

7B 10A

764

Student Edition TAKS Obj 2 Bio 8C TAKS Obj 2 Bio 10A TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 12B TEKS Bio 7B, 8B, 8C, 10A, 12B

Teacher Edition TAKS Obj 1 Bio/IPC 2B TAKS Obj 2 Bio 8C, 10A TAKS Obj 3 Bio 7B, 12B TEKS Bio 7B, 8B, 8C, 10A, 12BTEKS Bio/IPC 2B

pp. 764–765

AlternativeAssessmentHave students make a timeline ofthe evolution of vertebrates fromthe first jawless fishes throughamphibians. Next to each of theorganisms listed on the timeline,students should describe the newcharacteristics that arose in theorganism through natural selection.TAKS 1 Bio/IPC 2B

Answer to Concept Map

The following is one possible answer toPerformance Zone item 15.


• Science Skills Worksheet• Critical Thinking Worksheet• Test Prep Pretest• Chapter Test GENERAL

GENERAL

GENERAL

Chapter Resource File

can be

have skeleton of

Fishes

cartilaginousbonyjawless

cartilage

gills

operculum teleosts

countercurrent flow

have an most are

have

with

Key Concepts

Study CHAPTER HIGHLIGHTS

ZONEKey Terms

Section 1gill filament (747)gill slit (747)countercurrent flow (747)nephron (749)

Section 2lateral line (753)operculum (756)swim bladder (756)teleost (757)

Section 3lung (758)pulmonary vein (759)septum (760)

The Fish Body

● All fishes have gills and a backbone, and they circulate oxygen-rich blood from their gills directly to body tissues.

● Countercurrent flow maximizes the amount of oxygen thatcan be extracted from water.

● The four-chambered fish heart collects oxygen-poor bloodfrom the body and pumps it through the gills where itreceives oxygen. Oxygen-rich blood then circulates to therest of the body.

● A fish relies on its gills and a pair of kidneys to regulate itssalt and water balance.

● Most fishes fertilize their eggs externally as males andfemales release their gametes near one another in the water.

Today’s Fishes

● Hagfishes and lampreys are the only surviving jawlessfishes.

● Sharks have light, highly streamlined bodies well suited for rapid swimming, which makes them swift and efficient predators.

● Bony fishes are the most diverse and abundant group of fishes.

● Bony fishes have an internal skeleton made completely ofbone, a swim bladder, a lateral line sensory system, and aset of gill covers called opercula.

Amphibians

● Most amphibians have legs, breathe with lungs and throughtheir skin, and have two circulatory loops.

● Most amphibians supplement their oxygen intake throughcutaneous respiration—respiration through their moist skin.

● An amphibian lung is basically an air sac with a large surface area for gas exchange.

● The amphibian heart pumps oxygen-poor blood to the lungsand receives oxygen-rich blood from the lungs. The oxygen-rich blood is then pumped to the body.

● Salamanders are semiaquatic predators with tails, and caecilians are legless amphibians specialized for burrowing.

3

2

1

765

ANSWERS

Using Key Terms

1. d2. d3. c4. d5. a. A gill filament is the part of a

gill in which capillaries for gasexchange are found. A lung isthe entire organ used by manyterrestrial animals for gasexchange.

b. The swim bladder is an air-filled sac in bony fish thathelps the fish maintain buoy-ancy in water. The lateral lineis a structure in fish that con-tains groups of sensory cellsthat detect pressure and vibra-tions in the water.

c. Pulmonary veins return bloodto the heart from the lungs.The septum is a dividing wallin the heart.

Understanding Key Ideas

6. d7. b8. d9. a

10. d11. b12. a13. a Bio 5B

TAKS 2 Bio 8CTAKS 2 Bio 8CTAKS 2 Bio 10ATAKS 2 Bio 10ATAKS 2 Bio 10ATAKS 3 Bio 7BTAKS 2 Bio 8C

TAKS 2 Bio 8CTAKS 2 Bio 10ATAKS 2 Bio 10ATAKS 2 Bio 8C

14. Metamorphosis in amphibians takes place ingradual stages—from egg to tadpole to frog.In many insects, after the egg and larvalstages, a pupa is formed. After a period oftime, the adult form emerges. The adult looksquite different from the larva.

15. One possible answer to the concept map isfound at the bottom of the Study Zone page.Bio 3E

Bio 8B

Section Questions1 5, 6, 15, 16, 18, 212 1, 2, 3, 5, 7, 8, 9, 15, 17, 18, 223 4, 5, 10, 11, 12, 13, 14, 15, 18, 19, 20

Assignment Guide


CHAPTER 33

Using Key Terms1. Hagfish and lampreys are

a. bony fishes.b. scavengers.c. scaled, finless fishes.d. primitive fishes.

2. In bony fishes, the organ that senses pres-sure changes in water is thea. gill. c. operculum.b. septum. d. lateral line.

3. The organ in bony fishes that regulatesbuoyancy is the a. atrium. c. swim bladder.b. lateral line. d. conus arteriosus.

4. The group of amphibians that is legless is the a. toads. c. lampreys.b. skates. d. caecelians.

5. For each pair of terms, explain the difference in their meanings.a. gill filament, lungb. swim bladder, lateral linec. pulmonary veins, septum

Understanding Key Ideas6. Which of the following is not a key charac-

teristic of fishes? a. vertebral columnb. gillsc. single-loop circulationd. tympanic membrane

7. Which of the following shark characteristicsis not an adaptation for predation? a. streamlined bodyb. internal fertilization of eggsc. sharp, replaceable teethd. lightweight skeleton

8. Yellow perch and sharks share all of thefollowing characteristics excepta. gills.b. an internal skeleton.c. a single-loop circulatory system.d. a swim bladder.

9. A shark’s skeleton is a. composed of cartilage.b. composed of bone.c. very dense.d. quite rigid.

10. Most adult amphibians respire a. through their skin.b. through their skin and gills.c. through their lungs.d. through their skin and lungs.

11. Which of the following is not a characteris-tic of amphibians? a. lungsb. heart with two ventriclesc. cutaneous respirationd. double-loop circulation

12. Which of the following characteristics of leopard frogs is not an adaptation foravoiding predators? a. fast, flicking tongueb. skeleton adapted for jumpingc. cloacad. position of the eyes

13. How do tadpoles differ from frogs?a. Tadpoles have gills; frogs do not.b. Tadpoles are carnivorous; frogs are

herbivorous.c. Frogs show body symmetry; tadpoles

do not.d. Frogs live in water; tadpoles live in

damp vegetation.

14. Compare amphibian metamorphosis with insect metamorphosis. (Hint: SeeChapter 30, Section 3.)

15. Concept Mapping Construct a concept map describing the characteristicsof jawless, cartilaginous, and bony fishes.Try to include the following terms in yourconcept map: gills, countercurrent flow, cartilage, operculum, and teleosts.

PerformanceZONE

CHAPTER REVIEW

8C

7B

10A

10A

8C

8C

5B

8B

3E10A

8C

10A

10A

8C

766

Review and AssessTAKS Obj 1 Bio/IPC 2A, 2B, 2C, 2DTAKS Obj 2 Bio 8C, 10ATAKS Obj 3 Bio 7BTEKS Bio 3D, 3E, 5B, 7B, 8B, 8C,10A, 11A, 12CTEKS Bio/IPC 2A, 2B, 2C, 2D

pp. 766–767

Critical Thinking

16. Marine fish lose water to theirenvironment through osmosis, sothey drink a lot of sea water.Because sea water contains a highconcentration of salts, marinefish must actively pump excesssalt out of their body. Freshwaterfish actively take in salts fromtheir environment.

17. Yes, one could determine the ageof the carp by counting the num-ber of growth rings on one of itsscales.

18. Osmotic balance refers to theconcentration of salts in the bodyfluids. The operculum is thecover over the gills. Cutaneousrespiration is the process of tak-ing in oxygen through the skin.

19. No, most tadpoles are herbivoreswhereas adult frogs are carnivores.

Alternative Assessment

20. Tables will vary. The table shouldlist frogs and toads separatelyfrom salamanders and newts.Presentations will vary. Theyshould explain all features of thereference table.

21. Models should resemble thedrawings in Figure 2. Counter-current flow ensures that oxygendiffuses into the blood over theentire length of the capillaries inthe gills.

22. Ichthyologists study aspects offish anatomy, physiology, andecology. They are employed byfederal and state wildlife agenciesin park systems, by fish hatch-eries, and by zoos and wildlifeparks. Ichthyologists may also behired to conduct environmentalimpact studies when commercialdevelopment plans might affectfish habitats. Training require-ments vary according to position,but most positions require atleast a master’s degree. Growthprospects are fair. Starting salarywill vary by region. Bio 3D

TAKS 2 Bio 10A

TAKS 1 Bio/IPC 2A, 2B, 2C, 2D

TAKS 2 Bio 10A

TAKS 2 Bio 10A

TAKS 1 Bio/IPC 2C

Bio 11A

1. A. Correct. The diagram shows a single-loopcirculatory system which is a characteristic offishes, and the blood from the heart in the dia-gram is oxygen-poor (blue) and becomes oxygen-rich (red) after the X. Gills are the organsof gas exchange in fishes. B. Incorrect. Blood isbecoming oxygenated at the X, but the brainwould deoxygenate the blood. C. Incorrect.Lungs are not present in the single-loop systemof fishes. D. Incorrect. Other body parts woulddeoxygenate the blood.

2. F. Incorrect. See answer H. Amphibians do notlive in the deep ocean. G. Incorrect. See answerH. Amphibians do not live in coral reefs.

TAKS 2 Bio 10A


H. Correct. B is a double-loop circulatory sys-tem characteristic of amphibians, which can befound in moist land habitats. J. Incorrect.Although amphibians may be found near theedges of freshwater lakes, they are infrequentlyin the aquatic habitat of lakes.

3. A. Incorrect. Blood flows from the gills to thebody to the heart. B. Correct. Blood flows fromthe gills to the body, providing fully oxygenatedblood directly from the gills. C. Incorrect. Infishes, only oxygen-poor blood is pumped to thegills. D. Incorrect. Blood is pumped to bodyorgans at a lower pressure in single-loopcirculatory systems than in double-loopcirculatory systems. TAKS 2 Bio 10A

Bio 12C

Test

The diagrams below show two vertebratecirculatory systems. Arrows indicate the directionof blood flow. Use the diagrams and yourknowledge of science to answer questions 1–3.

1. Where are the capillaries labeled X located?A in the gills C in the lungsB in the brain D in other body organs

2. In which environment would you be mostlikely to find an animal that has circulatorysystem B?F deep ocean H moist habitat on landG coral reef J freshwater lake

3. Which statement applies to circulatorysystem A?A Blood returns to the heart from the gills

before being pumped to the rest of thebody.

B The body organs receive fully oxygenatedblood.

C A mixture of oxygen-rich and oxygen-poorblood is pumped to the gills.

D Blood is pumped to the body organs at a higher pressure than in circulatorysystem B.

Critical Thinking16. Inferring Relationships Explain how marine

and freshwater fishes differ in the way theymaintain their salt and water balance.

17. Recognizing Verifiable Facts A newspaperarticle reports that some carp in a localpond are approximately 50 years old. A rep-resentative from the State Department ofFish and Wildlife states that the claim canbe verified. How can this claim be verified?

18. Distinguishing Relevant InformationA student is writing a paper on theevolution of the heart. Which of the following terms do not pertain to hertopic? Explain. Sinus venosus, pulmonaryveins, septum, osmotic balance, atrium,operculum, conus arteriosus, and cutaneous respiration.

19. Justifying Conclusions Would you expectthe digestive system of a tadpole to func-tion like that of an adult frog? Explain.

Alternative Assessment20. Finding and Communicating Information

Use the media center or Internet resourcesto learn more about amphibians that live inyour area. Create an illustrated referencetable that includes their scientific andcommon names and information aboutsize, habitat, diet, and population size. Make the table available as a classroom reference. Prepare an oral orvideo presentation.

21. Forming a Model Construct a model that shows how water passes over the gillsof a bony fish. Then explain in writing whycountercurrent flow increases respiratoryefficiency.

22. Career Connection Ichthyologist Researchthe field of ichthyology (the study offishes), and write a report that includes ajob description, training required, kinds ofemployers, growth prospects, and starting salaries.


11A

2A 2B 2C 2D2C

10A

10A

10A

3D

12C

10A

10A

A B

If a question or an answer choice contains anunfamiliar term, try to break the word into parts to determine its meaning.

X

767

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