Chordates and Fish

Chordates

• 45,000 members

Must have the following• dorsal nerve chord – vertebrae• cranium – skull• endoskeleton of bone or

cartilage

7 CLASSES of VERTEBRAE

1. Mammalia

• hair, milk young

2. Aves

• birds : feathers, hollow bones

3. Reptilia

• dry scaly skin

4. Amphibia

• permeable skin

And 3 that are FISH!

5. Agnatha

• jawless fish • lampreys and hagfish• round mouth• long eel like bodies• gills evolved to…

Lamprey video

6. Chondrichthyes

• (kahn-Drick-theeez) • sharks, skates and rays• jaws and paired fins• cartilage skeleton• unique placoid scales

7. Osteichthyes

• (Ahs-tee-Ich-theeez) • bony fish : salmon, bass, etc.• jaws• skeleton of bone• lobe (mud) or ray finned

Largest Bony Fish

Longest Bony fish

Adaptations to live and Survive in Water

• trap gas = buoyancy• Trap in organ called gas

bladder/swim bladder• regulates depth with O2, CO2 and N2

Adaptations…

• streamline shape

Adaptations…

• muscular tail : Caudal fin

Adaptations…

• paired fins : 2 dorsal and 2 pelvic

Adaptations…

• mucus = less friction

Other escape adaptations

Puffer fish

Adaptations…

• gills : gas exchange O2 in and CO2 out

Adaptations…

• lateral line system :

nerves for sensing

vibrations in water

Adaptations…

• Separate sexes • internal and external

fertilization • spawning

Fish fighting