1. Marine Bio
Fish Unit Notes

2. Basic Information Phylum: Chordata
Sub Phylum: Vertebrata (vertebrates)
Characteristics:
Have backbone called- Vertebral Column or Spine
(Located on Dorsal side)
Function of vertebrae is the protect the nerve cord.

3. All vertebras are different..
Fish vs. Mammal
All vertebras are different..

4. Fish
Fish possess ‘spool shaped’ vertebrae.
Shark Vertebrae

5. Other Vertebrates
Other vertebrates, tetrapods, have vertebrae with protrusions.

6. Why? More support needed to support the force of gravity.
Attachment of ligaments & muscle

7. Cartilaginous Fishes Class Chondrichthyes
Sharks, Skates, Rays & Ratfish
Cartilage is lighter and more flexible then bone.
adds maneuverability
Rough skin, tiny scales (pointed) helps streamline fish
Moveable Jaws ( upper AND lower)
Well developed teeth ( modified scales)
many rows
replaceable
Always sharp.
Paired lateral fins makes swimming more efficient

8. Sharks are sometimes referred to as “ living Fossils” since many are very similar to species from 100 million years ago!!

9. Sharks
The Caudal fin of sharks often has a larger Dorsal lobe than Ventral lobe.
Two dorsal fins. The second is smaller, like a adipose fin of Salmonids.
Caudal Peduncle
Dorsal Lobe
Second Dorsal
mackerel shark
Ventral Lobe

10. Sharks cont.
They have 5-7 gill slits. Water flows through them instead of being forced.
Spiracles; round openings just behind the eyes. These allow water in while moving even if the mouth is closed.
This is very important for skates and rays.
Bottom feeders
Feed in sand & gravel
Most sharks swim continuously in order to maintain flow of water through gill slits.

12. Stingray
spiracle
Eye
Mouth

13. Teeth Teeth are actually modified “Dermal Denticles” (scales)
Dermis = Skin
Dent = Teeth
Skin, teeth
Shark skin was the first sand paper and is still used today in Japan to grind wasabi for sushi.

14. Skates and Rays Flattened bodies ( flattened vertically)
Exaggerated Pectoral fins “wings”
Bottom feeding, or filtered feeding
Spiracles located on dorsal side behind eyes

15. Ratfish
Live in deep water
Their gill slits are covered by skin flaps.

16. Bony Fish Class Osteichthyes 23,700 species
Comprise 98% of all fish and 50% of all vertebrates!
Posses thin, flexible, overlapping scales.

17. Bony Fish Class Osteichthyes
There are 23,700 species, I could go on but there are still more notes!

18. Osteichthyes cont.
Fins; the soft, thin membranes supported by bony spines. ‘Fin Rays’
Bony flap (operculum) covers gills.
Operculum ‘seals’ shut which means water is forcibly sucked into the mouth when it opens, and forced out when the mouth closes.

19. Osteichthyes cont. These have swim bladders for buoyancy.
They are gas filled, located above the stomach and intestines.
This adjusts buoyancy, but limits vertical movement in the water column.

20. Osteichthyes cont.
Both Osteichthyes and Chondrichthyes use a counter current flow in their gills.
This ensures that the most O2 will be transferred to the blood.

21. Blood never stops moving
Double pump system; an elaborate system of passing water over the gills while the fish stays stationary. There is no moment throughout the cycle when the water stops flowing.

22. Chondrichthyes vs. Osteichthyes
Scales
Cartilage
Tooth-like dermal Denticles.
Streamlined
Bony;
Flat, round and overlapping

23. Chondrichthyes vs. Osteichthyes
Teeth
Many rows
Sharp and serrated
Replaced when lost
Teeth point forward and backward to anchor prey.
Single row
Not replaced

24. Chondrichthyes vs. Osteichthyes Buoyancy
rely on light skeleton and oils contained in liver.
Can travel vertically in H2o column.
swim bladder
Limited in vertical travel

25. Chondrichthyes vs. Osteichthyes Fins
fins support by bones “rays”
can rotate
Hover
swim backwards
solid rigid fins
Cannot stop quickly or swim backwards
Cannot rotate fins

26. Chondrichthyes vs. Osteichthyes Reproduction
Internal fertilization using claspers, oviparous, ovoviviparous or viviparous.
Spawners
Mostly oviparous some ovoviviparous