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