1. Chapter 18
Fishes

2. Characteristics
Phylum: Craniata (describes the skull that surrounds their brain
Much evolution occurred in freshwater
Much evolution involved the movement of fish between fresh and marine environments
Over 41% of fish live in freshwater even though only small percentage of the Earth’s water resources is freshwater

3. Subphylum Hyperotreti: Hagfishes
20 species
Heads are supported by cartilage and brains enclosed in a fibrous sheath
Retain a notochord
4 pairs of sensory tentacles surrounding their mouths
Cold water marine habitats
Most primitive group in the craniata
Live buried in the sand and mud
Feed off of soft bodied invertebrates and scavenge dead and dying fish
Slimy skin

4. Subphylum Vertebrata: Ostracoderms
Extinct agnathans
Had bony armor as a defense
Bottom dwellers
Filter feeders

5. Subphylum Vertebrata: Hyperoartia- Class Cephalaspidomorphi
Lampreys
Found in freshwater and marine environments
Prey on other fish and their larvae as filter feeders
Mouth of an adult lamprey is suckerlike with lips that have sensory attachments
Have salivary glands with anticoagulant secretions and feed mainly on the blood of their prey

6. Lampreys
Adult lampreys live in the ocean or the Great lakes, at the end of their lives they migrate to freshwater to spawn
They build spawning nests in shallow water, a female attaches to a rock with her mouth, male use their mouth to attach to the female head and wrap themselves around the female
Eggs are shed in batches and fertilized externally and then covered in sand

7. Gnathostomata 1. 2 important evolutionary developments
Jaws: allowed for more efficient gill ventilation
Paired appendages: used to counteract the tendency to roll during locomotion and control the pitch of the the swimming fish
2 classes: cartilaginous and bony fish
Contain the armored fish which are extinct and acanthodians which are also extinct

8. Class Chondrichthyes Includes sharks, skates, rays and ratfishes
Most are carnivores or scavengers
Have biting mouthparts and paired appendages

9. Subclass Elasmobranchii
About 820 species
no swim bladders
Cartilaginous skeleton
Born with full sets of teeth

10. Tiger Sharks Found in tropical and temperate waters
Can grow up to 16 ft.
Solitary, nocturnal
Wide spectrum of food

11. Whale Shark Slow moving filter feeding shark
Largest: 41 feet and pounds
Found in warm oceans
Life span of 70 years

12. Whale Shark Feed mainly on plankton Docile
Does not pose a threat to humans

13. Hammerhead Shark Utilize electroreception

14. Distribution
Hammerhead sharks
Tiger sharks

15. Stingray http://video.nationalgeographic.com/video/stingray

16. Subclass Holocephali About 30 species Have an operculum: gill cover
Lack scales

17. Class Osteichthyes Bony fish
Have swim bladders: an internal gas filled organ that contributes to the buoyancy of fish

18. Subclass Sarcopterygii
Have muscular lobes associated with fins and use lungs in gas exchange
They survive stagnation by breathing with lungs but normally use gills

19. Coelacanths
Rare order of fishes that were thought to have been extinct but rediscovered in 1938

20. Osteolepiforms
Prehistoric lobe finned fish
Extinct

21. Subclass Actinopterygii
Ray finned fishes
Possess swim bladders
Sturgeons, paddlefishes

22. Sea Horses 54 species Class actinopterygii
Female deposits up to 1500 eggs in a male seahorses pouch who then carries them for up to 45 days till they emerge from pouch

23. Sea horses