1. Class Agnatha
80 species of hagfishes and lampreys
Skin lacks scales and plates
Cartilaginous skeleton, unpaired fins
Notochord remains throughout life
Some are parasitic
Hagfishes are marine; most lampreys
live permanently in fresh water
All lampreys reproduce in fresh water

2. Figure A hagfish

4. Figure A sea lamprey

5. Class Agnatha

6. Class Agnatha

8. Class Chondrichthyes
Includes:
Sharks
Rays
Skates

9. Class Chondrichthyes

10. Class Chondrichthyes

11. Figure Cartilaginous fishes (class Chondrichthyes): Great white shark (top left), silky shark (top right), southern stingray (bottom left), blue spotted stingray (bottom right)

12. Class Chondrichthyes Skeletons are made of cartilage
Skin is covered with placoid
scales

13. Sharks Mouth contains 6-20 rows of
teeth that point inward; when they break or wear down, the others move forward
Paired nostrils on the snout have specialized nerve cells that connect
with olfactory bulbs of the brain
Largest brain of all fish

14. Adaptations of Cartilaginous Fish
Most pump water over their gills
by expanding and contracting their mouth cavity and pharynx
Rays and skates have spiracles
located behind their eyes
Ammonia is converted to urea, which is much less toxic

15. Swimming generates lift and
many cartilaginous fish can store large amounts of low-density lipids in their livers to maintain buoyancy

16. Reproduction in Chondrichthyes
Fertilization is internal, a male transfers sperm using a modified pelvic fin called a clasper.
Sensory Functions
The lateral line system is present in
nearly all fish, which is a row of sensory structures that runs the length of the fish to detect vibrations in the water

17. Class Chondrichthyes

18. Class Osteichthyes – Bony Fish
Characteristics:
Bones
Lungs or Swim Bladder
Lungfishes have gills and
lungs
** All bony fish have an operculum
a hard plate that opens at the rear
and covers and protects the gills
Scales

19. Lobe-Finned Fishes
Have fleshy fins that are supported by a series of bones
7 species of lungfishes and one species of coelocanth exist today

20. The lungfish resembles a short bodied eel
The lungfish resembles a short bodied eel. The base color of the fish is brown with small spots all over.
They are carnivores. The dorsal and anal fins are long-based.

21. Figure 34.14 A coelocanth (Latimeria), the only extant lobe-finned genus

22. Ray-Finned Fishes
Have fins that are supported
by long, segmented, flexible
bony elements called rays.
includes eels, perch, salmon,
guppies, bass

23. Figure 34.13 Anatomy of a trout, a representative ray-finned fish

24. Figure 34.12a Ray-finned fishes (class Actinopterygii): yellow perch

25. Respiratory and Circulatory Systems
Water flows away from the head and
the blood flows toward the head. This countercurrent flow allows more oxygen to diffuse into the gills
Fish regulate their overall density by adjusting the amount of gas in their swim bladders
There are four chambers in the heart

26. Buoyancy in Fish
Squalene (liver oil)

27. Buoyancy in Fish

28. Physoclistous bladder
Buoyancy in Fish
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Physoclistous bladder

29. Respiration in Fish

30. Respiration in Fish

31. Osmoregulation in Fish

32. Reproduction Fertilization in most species is external
If internal fertilization occurs, the male
inserts his sperm into the female using
a modified anal fin; the female carries
the eggs inside her until the young are
born

33. Fish Reproductive Adaptations
Diadromous - fish that make “two runs” in their life to live and reproduce
Anadromous - fish that “run up” - salmon
Catadromous - fish that “run down” - eels
Parthenogenesis - no males required, females produce diploid eggs - Amazon molly