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Transparencies Standardized Test Prep

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Fishes and AmphibiansChapter 33

Table of Contents

Section 1 The Fish Body

Section 2 Today’s Fishes

Section 3 Amphibians



Section 1 The Fish Body

Objectives

• Describe the characteristics of modern fishes.

• Summarize how fish obtain oxygen.

• Summarize how blood circulates through a fish.

• Contrast how marine and freshwater fishes balance their salt and water content.

• Describe two methods of reproduction in fishes.

Chapter 33



Characteristics of Fish

Chapter 33 Section 1 The Fish Body



Key Characteristics of Modern Fishes

• All fishes share certain key characteristics:

1. Gills. Fishes normally obtain oxygen from water with their gills.

2. Single-loop blood circulation. Blood is pumped from the heart to the gills through the body and back to the heart again.

3. Vertebral column (backbone). All fishes have an internal skeleton made of either cartilage or

bone, with a vertebral column surrounding the spinal cord.




Gills

• The major respiratory organ of a fish is the gill. Gills are made up of rows of gill filaments—fingerlike projections through which gases enter and leave the blood.

• The gill filaments hang like curtains between a fish’s mouth and cheeks. At the rear of the cheek cavity is an opening called a gill slit.

• In countercurrent flow, water passes over the gills in one direction as blood flows in the opposite direction through capillaries in the gills.




Respiration in Fishes




Parts of Fish Gills and Countercurrent Flow




Circulation of Blood

• Fishes have a simple chamber-pump heart:

1. Sinus venosus. This collection chamber 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. Contractions of the ventricle pump the blood toward the gills.

4. Conus arteriosus. This chamber is a second pump that smoothes the pulsations and adds still more force.




Fish Heart Structure




Fish Heart and Single-Loop Circulation




Kidneys

• Although the gills play a major role in maintaining a fish’s salt and water balance, another key element is a pair of kidneys.

• Kidneys are organs made up of thousands of nephrons. Nephrons are tubelike units that regulate the body’s salt and water balance and remove metabolic wastes from the blood.

• Excess water and bodily wastes leave the kidneys in the form of a fluid called urine.




Fish Kidneys




Parts of a Nephron




Reproduction

• The sexes are separate in most fishes, and generally fertilization takes place externally.

• In a process called spawning, male and female gametes are released near one another in the water. A yolk sac within each egg contains nutrients the developing embryo will need for growth.

• The eggs of sharks, skates, and rays are fertilized inside the female’s body.




Section 2 Today’s Fishes

Objectives

• Distinguish between the three general categories of modern fishes.

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

• Summarize features of bony fishes.

Chapter 33



Jawless Fishes

• Lampreys and hagfishes have scaleless, eel-like bodies with multiple gill slits and unpaired fins.

• Their skeletons are made of cartilage, a strong fibrous connective tissue, and both kinds of fishes retain their notochord into adulthood.

• Hagfishes are scavengers of dead and dying animals on the ocean bottom.

• Most lampreys are parasitic on other living fishes.

Chapter 33 Section 2 Today’s Fishes



Cartilaginous Fishes

• Sharks, skates, and rays are cartilaginous fishes. Their skeletons are made of cartilage strengthened by the mineral calcium carbonate.

• The shark’s light, streamlined body allows it to move quickly through the water in search of prey. Its skin contains cone-shaped placoid scales, which give the skin a rough texture.

• Two smaller groups of cartilaginous fishes, the skates and rays, have flattened bodies that are well adapted to life on the sea floor.




Characteristics of Bony Fish




Bony Fishes

• Jawless and cartilaginous fishes are not as diverse as bony fishes, which are the most numerous of all the fishes.

• Bony fishes have a fully developed lateral line system. The lateral line is a sensory system that extends along each side of a bony fish’s body.

• The lateral line system also enables a fish to detect a motionless object by the movement of water deflected by that object.




Lateral Line in Fishes




Lateral Line System




Bony Fishes, continued

• Most bony fishes have a hard plate, an operculum, that covers the gills on each side of the head.

• Movements of certain muscles and of the opercula permit a bony fish to draw water over the gills, which enables the fish to take in oxygen.




Bony Fishes, continued

• Bony fishes contain a special gas sac called a swim bladder.

• By adjusting the gas content of the swim bladder, bony fishes can regulate their buoyancy.

• As the swim bladder fills, the fish rises, and as it empties, the fish sinks.




Swim Bladder




External Structure of Fish—Yellow Perch




Internal Structure of Fish—Yellow Perch




Anatomy of a Bony Fish




Ray-Finned Bony Fishes

• Ray-finned bony fishes comprise the vast majority of living fishes.

• Their fins are supported by bony structures called rays.

• Teleosts are the most advanced of the rayfinned bony fishes. Teleosts have highly mobile fins, very thin scales, and completely symmetrical tails.




Ray-Finned Fishes




Teleost




Ray-Finned Bony Fishes

• Ray-finned bony fishes comprise the vast majority of living fishes.

• Their fins are supported by bony structures called rays.

• Teleosts are the most advanced of the rayfinned bony fishes. Teleosts have highly mobile fins, very thin scales, and completely symmetrical tails.




Lobe-Finned Bony Fishes

• Only seven species of lobe-finned fishes survive today. One species is the coelacanth and the other six species are all lungfishes.

• In many lobe-finned fishes, each fin consists of a long, fleshy, muscular lobe that is supported by a central core of bones.

• The ancestor of the amphibians most likely was a third type of lobe-finned fish that is now extinct.




Section 3 Amphibians

Objectives

• Summarize the external and internal structures of the Eastern Lubber grasshopper.

• Compare complete and incomplete metamorphosis.

• Describe the characteristics of insects.

Chapter 33



Characteristics of Amphibians

Chapter 33 Section 3 Amphibians



Key Characteristics of Modern Amphibians

• Most amphibians share five key characteristics:

1. Legs

2. Lungs

3. Double-loop circulation

4. Partially divided heart

5. Cutaneous respiration




Key Characteristics of Modern Amphibians, continuedLungs

• A lung is an internal, baglike respiratory organ that allows oxygen and carbon dioxide to be exchanged between the air and the bloodstream.

• In amphibians, the lungs are hardly more than sacs with folds on their inner membrane that increase their surface area.

• Many amphibians also obtain oxygen through their thin, moist skin.




Amphibian Lung Structure




Respiration in Amphibians




Key Characteristics of Modern Amphibians, continuedDouble-Loop Circulation

• As amphibians evolved and became active on land, their circulatory system changed, resulting in a second circulatory loop.

• Amphibians have a pair of blood vessels not found in fishes, the pulmonary veins. The pulmonary veins 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.




Key Characteristics of Modern Amphibians, continuedDouble-Loop Circulation

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




Key Characteristics of Modern Amphibians, continuedCirculation of Blood

• A dividing wall known as the septum separates the amphibian atrium into right and left halves.

• The septum prevents the complete mixing of oxygen-rich and oxygen-poor blood as each enters the heart.

• A number of amphibians have a spiral valve that divides the conus arteriosus. The spiral valve also helps to keep the two streams of blood separate as they leave the heart.




Amphibian Heart Structure




Frog Heart and Double-Loop Circulation




Types of Amphibians




Frogs and Toads

• The order Anura is made up of frogs and toads that live in environments ranging from deserts to rain forests, valleys to mountains, and ponds to puddles.

• Adult anurans are carnivorous, eating a wide variety of small prey.

• The frog body, particularly its skeleton, is adapted for jumping, and its long muscular legs provide the power.




External Structure of a Frog—Leopard Frog




Internal Structure of a Frog—Leopard Frog




Anatomy of a Frog




Frogs and Toads, continued

Reproduction in Frogs

• Like most living amphibians, frogs depend on the presence of water to complete their life cycle.

• The female releases her eggs into the water and a male’s sperm fertilize them externally.

• After a few days, the fertilized eggs hatch into swimming, fishlike larval forms called tadpoles.

• Tadpoles develop into adult frogs through the process of metamorphosis.




Life Cycle of a Frog




Amphibian Life Cycle




Salamanders and Caecilians

• Salamanders have elongated bodies, long tails, and smooth, moist skin.

• Salamanders lay their eggs in water or in moist places. Fertilization is usually external.

• Unlike frog and toad larvae, salamander larvae do not undergo a dramatic metamorphosis.

• The young that hatch from salamander eggs are carnivorous and resemble small versions of the adults, except that the young usually have gills.




Salamanders and Caecilians, continued

Caecilians

• Caecilians (order Apoda) are a highly specialized group of tropical, burrowing amphibians with small, bony scales embedded in their skin.

• During breeding, the male deposits sperm directly into the female. Depending on the species, the female may bear live young or lay eggs that develop externally.

• Caecilians are rarely seen, and scientists do not know a lot about their behavior.




Multiple Choice

The diagrams below show two vertebrate circulatory systems. Arrows indicate the direction of blood flow. Use the diagrams to answer questions 1–3.

Standardized Test PrepChapter 33



Multiple Choice, continued

1. Where are the capillaries labeled X located?

A. in the gills

B. in the brain

C. in the lungs

D. in other body organs





1. Where are the capillaries labeled X located?

A. in the gills

B. in the brain

C. in the lungs

D. in other body organs





2. In which environment would you be most likely to find an animal that has circulatory system B?

F. deep ocean

G. coral reef

H. moist habitat on land

J. freshwater lake





2. In which environment would you be most likely to find an animal that has circulatory system B?

F. deep ocean

G. coral reef

H. moist habitat on land

J. freshwater lake





3. Which statement applies to circulatory system A?

A. Blood returns to the heart from the gills before being pumped to the rest of the body.

B. The body organs receive fully oxygenated blood.

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

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





3. Which statement applies to circulatory system A?

A. Blood returns to the heart from the gills before being pumped to the rest of the body.

B. The body organs receive fully oxygenated blood.

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

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


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