1. Fish

2. Fish
Vertebrates- Have a backbone that encloses and protects a nerve cord.
Estimated 22,000 species of fish
Fish make up half of all vertebrate species on Earth.
58% of fishes are marine fish

3. Classification Phylum Chordata Subphylum Vertebrata Class Agnatha
Class Chondrichthyes
Class Osteichthyes

4. Agnatha Jawless Fish Most primitive of all living fish
Skeleton made of cartilage
Feed by suction; round, muscular mouth with rows of teeth
Eel-like shaped body
Lack paired fins and scales
Examples: Hagfish and Lamprey

5. Hagfish About 20 species Live in tunnels dug in muddy bottoms
Cold water at moderate depths
Maximum length of 2.5 feet long
Eat dead dying fish

6. Hagfish

7. Lamprey About 30 species Usually Freshwater
Some breed in rivers and move to the ocean as adults
Parasitic- Attach to other fish using sharp teeth and suck their blood

8. Lamprey

9. Chondrichthyes Cartilaginous Fish
Skeleton made of cartilage, lighter and more flexible than bone
Teeth, vertebrae, and jaw may become calcified, but are not true bone
Mouth located on ventral side
Movable jaws with well developed teeth
Paired lateral fins
Rough skin of scales called denticles, come from same tissue layer as teeth
Examples: Sharks, skates, and rays

10. Denticles

11. Sharks About 350 species 25 species found in Gulf of Mexico
Found in all depths and temperatures, but most found in tropical, coastal waters
Some sharks like the bull shark can travel up rivers.

12. Shark structure
Fins
1-2 dorsal fins on top
Paired pectoral fins for lift as it swims
Paired pelvic fins used to stabilize
Single anal fin for extra stability
Caudal fin with 2 lobes, used to propel shark
Lack swim bladders; Buoyancy provided by oil filled liver (up to 25% of body wt.)

13. Fins

14. Shark structure
Streamlined shape reduces drag and lowers energy output during swimming.
Fusiform shape- round in middle and tapered at both ends
Coloration- most use countershading
Dorsal side is darker than ventral side
Harder to see when looking down (dark) or when looking up toward light.

15. Respiration Most swim continuously to get oxygen
Exception: Nurse shark
“Resting” uses 9% more energy to move water over gills
5-7 gill slits, no operculum
Some sharks have spiracles located behind eye, takes oxygen directly to eye and brain, or for breathing at rest

16. Diet Sharks known as “trash eaters”
Feed on fish, crustaceans, marine mammals, mollusks, and turtles
Take advantage of slow, injured, or sick prey
Filter Feed, Ex: whale shark
Obtain water through osmosis

17. Whale Shark

18. Senses
Good vision, deeper dwellers have larger eyes for low light level
Some species have nictitating membrane that protects eyes when hunting
Taste buds in mouth, no tongue
Smell- can detect a drop of blood 0.25 miles away
Lateral Line- detect movement up to 3000 ft. away

19. Ampulla of Lorenzini
Sense organ located in the pits of the shark’s snout
Can detect electrical activity given off by muscles and nerves of other organisms
Can also detect creatures buried in the sand

20. Reproduction Internal Fertilization Clasper- male copulatory organ
Oviparous- lay eggs
Viviparous- live birth
Ovoviviparous- eggs hatch inside mother
No parental care given

21. Info Most active at twilight and dark hours
32 species of shark known to attack humans
Mostly Asocial (hammerheads can be found in schools)
Symbiotic Relationships
Pilotfish-swim w/ shark and eat food scraps
Cleaner Wrasse- picks off parasites
Remora fish- attach to sharks and eat parasites

22. Rays and Skates About 500 species Flattened bodies, hide on bottom
Found in Temperate and Tropical seas
Few Freshwater species in Amazon
5 pairs of gill slits located on ventral side (underneath), spiracles also
Mouth on ventral side

23. Rays and Skates continued
Pectoral fins greatly expanded; fused to head
Eyes located on top of head
Live birth
Feed mainly at night
Strong sense of smell, lateral lines detect vibrations, and electro-receptors that detect impulses of prey