What is fish with out an eye.

FSH

History• Earliest fish had no jaws

and no paired fins-filtered feed

• 1st fish bodies covered with bony plates

• For 100 million years-fish were the only vertebrates

Superclass Agnatha• Jawless vertebrates• Most primitive, living

vertebrates• Ostracoderms (extinct);

lamprey and hagfish• Lack paired appendages;

cartilaginous skeleton; notochord throughout life; rasping mouth

Superclass Gnathostomata, I• Placoderms (extinct): first with hinged jaws and paired appendages• Class: Chondrichthyes~ Sharks, skates, rays• Cartilaginous fishes; well developed jaws and paired fins; continual water

flow over gills (gas exchange); lateral line system (water pressure changes)

Rise of Sharks & Bony Fish

• About 400 mya all the other fish disappeared and were replaced by sharks and bony fish.

• The jaws improved-developed the hyomandibular arch from gills

• More fins developed.

Continue• Sharks became the top predators-skeletons of cartilage

• Sharks first fish with bony teeth

• Sharks use internal fertilization and pups born alive

• Skates and ray develop around 200 mya

Life cycles:Oviparous- eggs hatch outside mother’s bodyOvoviviparous- retain fertilized eggs; nourished by egg yolk; young born liveViviparous- young develop within uterus; nourished by placenta

Bony Fish

• Evolved 400 mya• Developed heavy bony skeleton for protection

and anchoring of muscles• Evolved in fresh water• Developed two types

– Ray finned most fish perch- has swim bladder-95% of all fish are teleosts (advanced ray finned fish)

– Lobe finned evolved 390 mya-fin is more like limb than fin-EX :Coelacanth

• Some lobed-finned fish walk on land

Key Adaptations

• 1. Gills for breathing• 2. Backbone• 3. Single looped circulation system- blood is

pump from heart to gills to body back to heart• Nutritional requirements fish are unable to

make all the amino acids needed so they must get these amino acids by eating them- (true for all vertebrates)

Superclass Gnathostomata, II• Class: Osteichthyes• Ossified (bony) endoskeleton; scales operculum(gill covering); swim

bladder (buoyancy)• Most numerous vertebrate• Ray-fined (fins supported by long, flexible rays): bass, trout, perch,

tuna, herring• Lobe-finned (fins supported by body skeleton extensions): coelocanth• Lungfishes (gills and lungs): Australian lungfish (aestivation)

Bony Fish adaptations• Swim bladder secrets and absorbs gases in order to make fish

rise or sink in water-gas is CO2

• Lateral line system sensory organ located along the side of a fish (hearing)

• Gill cover (operculum) hard plate covering the gills that pumps to push water over gills (so fish doesn’t have to swim to breath.)

Homework

• Draw a picture of a fish and label each fin-determine what each fin does.