1. Agnatha Chondrichthyes Osteichthyes
FISHES
Agnatha
Chondrichthyes
Osteichthyes

2. General Characteristics
Ectothermic (Cold-blooded)
Vertebrates
Have scales
Swim with fins
Almost all exclusively aquatic
Filter oxygen from water over gills

3. Scale Types Cycloid – smooth surface, on bony fish
Carp
Salmon
Ctenoid – teeth along ridge (rough to touch), on bony fish
Bass
Bluegill
Perch

4. Ganoid – hard, interlocking, diamond-shaped, on primitive fish
Scale Types
Placoid – Look like tiny teeth, feel like sandpaper, on cartilagenous fish
Sharks
Rays
Ganoid – hard, interlocking, diamond-shaped, on primitive fish
Gar

5. Maintaining Buoyancy Swim bladder Liver Uses air Most bony fishes
Can be used as a second “lung”
Liver
Uses oil
Sharks
Most sharks must constantly swim to avoid sinking

6. Use fins and body wall to push against water
Locomotion
Use fins and body wall to push against water
Forked tails reduce drag in the water
Muscles in a zig-zag shape
Each contraction moves large parts of the body wall

7. Gills Obtain oxygen Give off carbon dioxide
Most have an operculum (hard plate that protects the gills)
Oxygen dropped into circulatory system pumped by 2-chambered heart

8. Gas Exchange
Exchange of gases occurs in capillary network in gill lamellae; water and blood flow in opposite directions over lamellae = Countercurrent Exchange

9. Countercurrent Exchange System

10. Excretion and Osmoregulation
Freshwater fishes
never drink
Lots of nephrons
Ions are reabsorbed
Marine fishes
Drink constantly
Less blood is filtered
Water is reabsorbed

11. Limited vision, focus by moving lens back and forth (no eyelids)
Senses
Limited vision, focus by moving lens back and forth (no eyelids)
Olfactory receptors
Magnetic receptors
Touch

12. Sense (cont.)
Hearing – sound conducted through skull
Lateral line system – senses movement of other organisms around them
Electroreception – sense electrical impulses generated by muscle twitches

13. Reproduction Oviparous (most fish)
Release eggs, young develop outside mom
Ovoviviparous (some cartilaginous fishes)
Eggs remain inside mom
Eggs at a later stage of development before they are released
Viviparous (a few sharks)
Young born alive

14. Chondrichthyes – Cartilagenous Fish
Classes of Fish
Agnatha – Jawless Fish
Ex. Lamprey & Hagfish
Chondrichthyes – Cartilagenous Fish
Ex. Sharks, Skates, and Rays
Osteichthyes – Bony Fish
Ex. All other fish

15. Fish Research- Groups Type of fish Habitat
Physical features (body shape, # of fins, type of fins, scales, etc.)
Color(s) of fish seen
Adaptations

16. Groups Agnatha Class- Lampreys Agnatha Class- Hagfish
Chrondrichthyes- Sharks
Chrondrichthyes- Skates and Rays
Osteichthyes- Fresh water
Osteichthyes- Saltwater water

17. Class Agnatha Cartilagenous Simplest and oldest vertebrates Jawless
No scales
Scavengers or parasites
Lamprey, hagfish

19. Class Chondrichthyes
Hinged jaw
Paired fins
Scales
Muscles attached to skin, not skeleton
Cartilagenous skeleton

20. Jaws not attached to brain case
Sharks
Jaws not attached to brain case
Can protrude during attack
20 tons per square inch for an 8’ shark
Size varies (few inches to over 40 feet)
Variable body shapes

21. Skates and Rays
Wing-like pectorals
Most live on sea beds
Some have poison spines on backs or tails (stingrays)

22. Class Osteichthyes
Largest group of fishes
Skeleton made of bone and cartilage
Hinged jaws
Paired fins
Hard, protective scales
Covered gills (operculum)