1. Chapter 18- Fish

2. Vertebrate Chordates
Phylum Chordata- internal skeleton of cartilage or bone; vertebrae surrounding the dorsal nerve cord (develops from notochord).
Fish
Aquatic
Gills
Fins;covered in scales
Pectoral fins- located on anterior portion
Pelvic fins – located on posterior portion
Dorsal fin – located on dorsal area
Caudal fin- tail fin
Post anal fin – sticks out past the cloaca
Two-chambered heart
All vertebrates developed from fish
Fins developed into jointed appendages
Ectothermic

3. Gills
Pharyngeal pouch – Small pocket at the back of throat that becomes the gills
Rows of gill filaments (fingerlike projections through which gases enter and leave the blood)
Gill slit- Opening at rear of the cheek
Operculum- Covers gills and draws water into fish’s mouth
Countercurrent flow- Water passes over gills in one direction as blood flows in opposite direction through capillaries
85% extraction of dissolved oxygen from water

4. Blood Circulation Heart pumps blood to the gills
Sinus venosus- Collects oxygen-poor blood from body
Atrium- Delivers to ventricle
Ventricle- Pumps blood to gills
Conus arteriosus- Smooths flow of blood
Oxygen-rich blood leaves gills to go to the rest of the organs

5. Fish Heart Structure

6. Kidneys and Reproduction
Kidneys- Organs made of 1,000s of nephrons
Nephron- Tube-like unit regulates the body’s salt and water balance and removes waste from blood
Excess water and waste-urine
Reproduction
Most separate sexes
External fertilization (spawning)
Yolk sacks supply nutrients-stay attached to hatchlings
Large numbers of eggs released to ensure some survive
Sharks, skates, and rays have internal fertilization
Claspers- Male organs used to insert sperm into female

7. Subphylum Hyperotreti
Class Myxini
Hagfish
Craniata- Partial cranium (skull); no vertebrae
Cartilage skeleton
Lack jaws
4 pairs of tentacles around mouth

8. Subphylum Vertebrata 43,700 species
Skeleton (cartilage or bone); grows as the animal grows
Complete digestive system and a large coelom
Closed circulatory system
Respiration by: gills, lungs, and in some cases, moist skin

9. Class Cephalasidomorphi- Lampreys
Agnatha ("no jaws") or the Cyclostomata ("round mouth").
Long, eel-like, jawless fish
No paired fins
Free-swimming predators
Hatch in freshwater; Some migrate to the sea, return to freshwater to reproduce

10. Range of Lamprey in n. America

11. Fish Trivia

12. Ostracoderms First were Placoderms- extinct Heavy armor plated
Strong jaws-modified gill arches
Paired pectoral and pelvic fins allow for better escape and predation

13. Gnathostomata Jaws evolved from anterior pair of pharyngeal arches
The skeletal supports for the pharyngeal slits
More efficient gill ventilation and capture and ingestion of food
Paired appendages

14. Class Osteichthyes- Bony fish
20,000 species
Marine and freshwater
Lateral line system- Sensory system extending on each side
Sensory cells with cilia detect vibrations to allow a fish to perceive its position in the water
Optic tectum – Area in a fish’s brain that receives and processes info from visual, auditory and lateral line systems
Two groups: the lobe-finned (Sarcopterygii) and ray-finned fish (Actinopterygii)

15. Sarcopterygii: Lobe-finned fish
6 species of lungfish
Found in stagnant or freshwater ponds
Africa, South America, and Australia.
1 species of coelacanth
deep oceans
crossopterygian fish
Muscular fins with large, jointed bones attaching the fins to the body
Become limbs of amphibians during evolutionary descent

16. Lung Fish & Coelacanth

17. Actinopterygii: Ray-finned fish
Thin, bony supports with radiating bones
Filter feeders and predators
Swim bladder- a gas-filled sac that regulates buoyancy and depth
External fertilization
Teleosts- 95% of all living fish
Examples: tuna, bass, perch, catfish, eels, and trout

18. Trout, Swordfish, and Flounder

19. Eel

20. Class Chondrichthyes 850 species of skates, rays, and sharks
Jaws, lots of teeth, paired fins, and a cartilage endoskeleton
5 to 7 gill slits on both sides of the pharynx lack gill covers

21. Class Chondrichthyes- Sharks
Teeth of sharks are enlarged scales
Largest sharks are filter feeders (Basking and whale sharks)
Most sharks are fast-swimming, open-sea predators

22. Basking and Whale Sharks

23. Class Chondrichthyes (Elasmobranchia)- Rays and Skates
Family Rajidae of the order Rajiformes
Live on ocean floor
Pectoral fins enlarged into wing-like fins
Swim slowly
Venomous spine
Countershading- Bottom is lighter while top is darker
Electric ray stun with over 300 volts
Rays are live-bearing while skates are egg laying

24. Sawfish
Sawfish rays have large anterior "saw" -use to slash through schools of fish