PHYLUM CHORDATA
• Dorsal Notochord-long rod that supports the body-becomes the vertebrae in most.
• Dorsal Nerve cord-becomes the central nervous system.
• Pharyngeal gill slits-openings in the throat for feeding & breathing-becomes the Pharynx in humans.
• Tail-forms in embryos and extends past the anus.
Evolution of FishesEvolution of Fishes
Primitive fishes lacked Primitive fishes lacked jawsjaws and and paired finspaired fins
Ancestral jawless fish ruled the seas Ancestral jawless fish ruled the seas during during Devonian Period: Age of Devonian Period: Age of FishesFishes
Evolution of Fishes
CLASS PISCES: CLASS PISCES: FISHESFISHES
CLASS PISCES
BECAUSE THEREARE 20,000 SPECIES
THERE ARE 3SUBCLASSES
SUBCLASS AGNATHA
(JAWLESS FISH)
CHONDRICHTHYES(CARTILAGE)
OSTEICHTHYES(BONY FISH)
SUBCLASS SUBCLASS
Jawless Fishes = Jawless Fishes = AgnathansAgnathans
No true teeth/jawNo true teeth/jaw Skeleton made of fibers/cartilageSkeleton made of fibers/cartilage CartilageCartilage-strong supporting tissue -strong supporting tissue
(softer/more flexible than bone)(softer/more flexible than bone) Lack true vertebrae (keep notochord Lack true vertebrae (keep notochord
as adults)as adults) ONLY VERTEBRATE PARASITES!ONLY VERTEBRATE PARASITES! 2 groups: Lampreys and Hagfishes2 groups: Lampreys and Hagfishes
LampreysLampreys ParasitesParasites Sucker-like oral disks with teeth to Sucker-like oral disks with teeth to
grasp and suck tissues/fleshgrasp and suck tissues/flesh
HagfishesHagfishes
DetritivoresDetritivores No eyesNo eyes Toothed Toothed
tonguetongue Secrete slimeSecrete slime 6 hearts6 hearts Tie into knotTie into knot
Hagfish
Cartilaginous Fishes = Cartilaginous Fishes = ChondrichthyesChondrichthyes
Sharks, Rays, SkatesSharks, Rays, Skates Cartilage skeleton (no bone)Cartilage skeleton (no bone) Sharks have thousands of teeth in Sharks have thousands of teeth in
rowsrows Skates and Rays glide with wing-like Skates and Rays glide with wing-like
pectoral fins (bottom-dwelling)pectoral fins (bottom-dwelling)
CARTILAGINOUS FISHCARTILAGINOUS FISH 850 Species of 850 Species of
Sharks, Rays, & Sharks, Rays, & SkatesSkates
Skeleton is made of Skeleton is made of cartilage. S-shaped cartilage. S-shaped swimming/rigid fins.swimming/rigid fins.
External Gill slits.External Gill slits. Store oils & constant Store oils & constant
motion to stay afloat.motion to stay afloat. Scales are small bony Scales are small bony
plates (at one time plates (at one time used as sandpaper).used as sandpaper).
RAYS & SKATESRAYS & SKATES Flattened body for a Flattened body for a
bottom-dwelling nichebottom-dwelling niche Spiracles & eyes on Spiracles & eyes on
the dorsal side.the dorsal side. Mouth, nostrils & gill Mouth, nostrils & gill
slits on ventral side.slits on ventral side. Stingrays have a Stingrays have a
hollow barb.hollow barb. Manta ray grows to Manta ray grows to
18’.18’.
SHARKSSHARKS Close to 300 species.Close to 300 species. Largest fish in the Largest fish in the
world-Whale Shark.world-Whale Shark. Can smell 1drop/bloodCan smell 1drop/blood
In 1 million parts/water.In 1 million parts/water. Lateral line detect Lateral line detect
vibrations in the watervibrations in the water Ampullae of LorenziniAmpullae of Lorenzini
Sense changes in Sense changes in electrical field.electrical field.
WHALE SHARKWHALE SHARK
Bony Fishes = Bony Fishes = OsteichthyesOsteichthyes
BoneBone skeleton (hard, calcified skeleton (hard, calcified tissue)tissue)
Ray-Finned FishesRay-Finned Fishes-fins formed -fins formed from bony spines covered by thin from bony spines covered by thin layers of skin (largest group)layers of skin (largest group)
Lobe-Finned FishesLobe-Finned Fishes-fleshy fins with -fleshy fins with bones (some jointed like arms/legs)bones (some jointed like arms/legs)…ex. Lungfish & Coelacanth…ex. Lungfish & Coelacanth
Fish:
Anal fin
Eye
Mouth
Dorsal fin Caudal fin
Operculum (gill cover) Pelvic fin Pectoral fin
Lateral line
Scales
•Aquatic Vertebrates•Paired Fins
•Scales•Gills
FeedingFeeding
Herbivores, carnivores, parasites, Herbivores, carnivores, parasites, filter feeders, and detritivoresfilter feeders, and detritivores
Digestive tract: Digestive tract: mouthmouthesophagusesophagusstomachstomachpyloripyloric cecac cecaintestineintestineanus (solid waste)anus (solid waste)
Enzymes added by liver and Enzymes added by liver and pancreaspancreas
Mouth
Esophagus Stomach
Pyloric cecum Liver
Pancreas
Intestine
Anus
Digestive System
RespirationRespiration
GillsGills on sides of pharynx to exchange on sides of pharynx to exchange gasesgases
Gill FilamentsGill Filaments-feathery structures -feathery structures with capillaries for gas exchangewith capillaries for gas exchange
Gill RakersGill Rakers-prevents prey from -prevents prey from escaping through gillsescaping through gills
Gill ArchesGill Arches-support and protect gills-support and protect gills OperculumOperculum-protective bony cover -protective bony cover
over gill openingsover gill openings
Gills
LungfishLungfish
Adaptation to Adaptation to oxygen-poor oxygen-poor waterwater
Tube brings Tube brings oxygen from air oxygen from air into fish’s mouth into fish’s mouth to “LUNG”to “LUNG”
CirculationCirculation
Closed systemClosed system 2 chambered heart2 chambered heart Single loop: heartSingle loop: heartgillsgillsbody (back body (back
to heart)to heart)
Fish HeartFish Heart
Sinus VenosusSinus Venosus-sac that collects -sac that collects oxygen poor blood from veins; sends oxygen poor blood from veins; sends blood toblood toAtriumAtrium-large muscular -large muscular chamber; sends it tochamber; sends it toVentricleVentricle--large muscular chamber that large muscular chamber that pumpspumps blood; sends it toblood; sends it toBulbus Bulbus ArteriosusArteriosus-muscular tube that -muscular tube that connects toconnects toAortaAorta-large blood -large blood vessel that sends blood to gillsvessel that sends blood to gills
Sinus Venosus Atrium
Ventricle
Bulbus arteriosus
Fish Heart
Body muscle circulation
Brain and head circulation
Heart Digestive system circulation
Gills Circulation in a Fish
ExcretionExcretion Eliminate nitrogenous waste as Eliminate nitrogenous waste as
ammonia (urine)ammonia (urine) Kidneys filter waste from bloodKidneys filter waste from blood Diffusion through gillsDiffusion through gillsKidney
Brain
•Well-developed nervous system with brain
•Eyes with color vision
•Taste/Smell
•Lateral Line System- detect currents/vibrations in water (sense nearby fishes)
Response/Nervous System
Olfactory Bulbs-smell (olfaction)Cerebrum-smell (and voluntary activities)Optic Lobe-process info from eyesCerebellum-coordinates body movementsMedulla Oblongata-controls internal organs
Olfactory bulb
Cerebrum
Optic lobe
Cerebellum
Medulla oblongata
Movement• Swim Bladder-internal gas filled organ to
adjust buoyancy in bony fish only
Movement continued…Movement continued…
Contract paired sets of musclesContract paired sets of muscles Fins propelFins propel Dorsal/Ventral fins for stability Dorsal/Ventral fins for stability
((Dorsal/Anal)Dorsal/Anal) Paired fins for fine Paired fins for fine
movements/turning movements/turning ((Pectoral/PelvicPectoral/Pelvic))
CaudalCaudal fin for speed fin for speed
ReproductionReproduction
External/Internal fertilizationExternal/Internal fertilization OviparousOviparous-eggs (embryo) develop and -eggs (embryo) develop and
hatch outside mom’s body; obtain food hatch outside mom’s body; obtain food from egg yolkfrom egg yolk
OvoviviparousOvoviviparous-eggs stay in mom’s body; -eggs stay in mom’s body; obtain food from egg yolk; young are obtain food from egg yolk; young are “born alive”“born alive”
ViviparousViviparous-embryos stay in mom’s body; -embryos stay in mom’s body; obtain food from mom; young are born obtain food from mom; young are born alivealive
•Anadromous-live in ocean but migrate to fresh water to breed; Ex. Salmon
Migrations
• Catadromous- Breed in the oceans but live in freshwater
• Eels migrate to the Sargasso Sea, they spawn at depths of 300 meters and die when done