1. Today’s Fishes
Section 33.2

2. Jawless Fish - Agnathans
Lampreys and hagfish
Scaleless
Eel-like bodies
Multiple gill slits
Unpaired fins
Skeletons of cartilage
Hagfish – ‘vultures of the sea’ scavengers
Lamprey – parasites on other living fish

3. Hagfish

4. Lampreys

5. Cartilaginous Fishes Sharks, skates and rays
Skeletons made of cartilage strengthened with calcium carbonate – lightweight and strong
Streamlined body
Placoid scales – give skin a rough texture
Teeth are modified scales and are replaced as needed throughout lifetime

6. Shark

7. Skate roundish or triangular shape

8. Ray kite-shaped with 1 or more venomous barbs in the tail

9. Bony Fishes Largest group of fish Endoskeleton made of bone
Lateral line system – acts as a sensory organ to detect movement in the water (theirs and other objects)
Operculum – hard gill cover which allows fish to move water over the gill while remaining still in the water
helps fish conserve energy
Swim bladder – allows fish to maintain water depth
gas in  fish rises; gas out fish sinks
Two groups: ray-finned fish & lobe-finned fish

10. Ray-finned fish Most fish are in this group
Teleosts – the most advanced
Highly mobile fins
Very thin scales
Completely symmetrical tails
95% of all fish species

11. Yellow perch – a ray-finned fish

12. Lobe-finned fish Only 7 species – 1 coelacanth + 6 lung fish
Each fin has a long, fleshy, muscular lobe supported by a central core of bones
May be a direct ancestor of amphibians, but probably not

13. Coelacanth

14. Lung fish