1. Marine Fishes
Class Osteichthyes – Bony fishes; the most prominent group of vertebrates, they
include about 24,000 species.
In addition to having a
bony skeleton,
there are some other
major differences
between bony and
cartilaginous fishes.

2. Marine Fishes
Bony and cartilaginous fishes also have very different strategies for maintaining their
position within the water column.
Most bony fishes use a swim bladder for lift, whereas most sharks rely on the
swimming generated lift that is a function of the fluid dynamics of their fins and tail.
Both groups do however use bands of muscle called myomeres to generate the basic
undulating motions of the body.
There are many exceptions though…

3. Marine Fishes There is however great variation
to the basic themes of movement,
as well as the body shapes that
are best adapted to different
environments and different
swimming habits…

4. Marine Fishes - Coloration
The color of bony fishes is typically found in special cells in the skin called
chromatophores.
Different chromatophores, each with varying amounts of pigments, can dictate
the basic color pattern of the different fishes.
Many fishes can even change their coloration based on their environmental
conditions (for predation, avoidance of predation, and communication with
others of the same species).
Examples of general fish coloration patterns:
Warning coloration
Cryptic coloration
Disruptive coloration
Countershading

5. Marine Fishes – Circulatory System
The circulatory system of all fishes are based on a two-chambered hearts that pump
blood to the gills, from where the oxygenated blood is carried to the body
through arteries and capillaries, before returning to the heart through the
veins.

6. Marine Fishes – Circulatory System
The mechanism for irrigating the gills is different for bony and cartilaginous fishes.
Cartilaginous fishes:
Bony fishes:

7. Spiracles

8. Marine Fishes – Circulatory System
Gas exchange occurs in the gills,
where a counter-current flowing
blood/water system allows for
very efficient oxygenation of the
blood…

9. Marine Fishes – Reproductive System
A few species of fishes are hermaphroditic, but most have separate sexes… Sexes
are not always definitive though, with many species exhibiting sex reversal.
What are the advantages of each of these strategies?
Depending on the species of the fishes, they all have a wide range of behaviors
associated with mating. Also, different species exhibit internal versus external
fertilization; and, oviparity, viviparity, and ovoviviparity strategies are
all utilized…
What may be the advantages and disadvantages of each?

10. Broadcast Spawning

11. Coelacanth Evolution

13. Scales: 4 types (fig. 8.8)
1. Ganoid: Bony scales found in oldest known species including sturgeon.
2. Cycloid: Simple thin disc lik escales with smooth surface which have circular rings to determine growth.
3. Ctenoid: same as cycloid, but have been found in most advanced teleosts which have posterior spikes from scales. Perch
4. Cosmoid: Similar to placoid scales and probably evolved from the fusion of placoid scales.

14. Ganoid
Ganoid scales of the Florida Gar, Lepisosteus platyrhincus. Photo: C. Bento © Australian Museum

15. Ctenoid & Cycloid Scales

16. Sturgeon

17. Cycloid
Cycloid scales of Jungle Perch, Kuhlia rupestris. Photo: C. Bento © Australian Museum

18. Cycloid Rainbow Trout on lower left

19. Ctenoid
Dried scale of a Barramundi showing the growth rings, or annuli
Ctenoid scales of the Paradise Fish, Macropodus opercularis. Photo: S. Lindsay © Australian Museum

20. Ctenoid Scales Sole & Sea Perch

21. Cosmoid
Cosmoid scales of the Queensland Lungfish. Photo: C. Bento © Australian Museum

22. Red muscles
Game fish have large amounts of red muscles which contain more blood vessels = more energy and O2.
Red muscles produce greater heat energy b/c separate smaller blood vessels carry oxygenated blood to muscles and not dorsal aorta. The blood vessels are close to the veins which are 10 degrees warmer, thus heating the blood, producing more power.

23. Red Muscle - Myomeres

25. Cryptic coloration (fig 8.10a)
a pattern of pigmentation that allows an organism to blend into the background of its preferred habitat.

26. Disruptive Coloration(fig.8.28, 14.30)
Color stripes, bars, or spots

27. Warning Coloration(fig.8.10c)
Dangerous, poisonous, or taste bad

28. Countershading
Dark top, light bottom

29. Symbiotic Relationships
1.Several species of small bony fishes, such as the cleaner wrasse (Labroides dimidiatus), are "cleaners" that eat debris and parasites from the skin and scales of larger fishes.

30. Symbiotic Relationships
2.Remoras (family Echeneidae) commonly attach themselves to sharks or other large fishes, whales, and sea turtles using a modified dorsal fin. They eat scraps left over from the meals of their hosts. They may eat parasites as well.

31. Symbiotic Relationships
3.Some bony fishes have symbiotic relationships with nonfish species. Clownfishes (family Pomacentridae) live unharmed among the venomous tentacles of sea anemones, which protect the clownfish from potential predators

32. Commensalism
a situation in which two organisms are associated in a relationship in which one benefits from the relationship and the other is not affected much. The two animals are called commensals.
The word derives from the Latin com mensa, meaning sharing a table.
+ and 0 = Commensalism.

33. Mutualism
+ and + = Mutualism. Both species benefit by the interaction between the two species.
Examples???
Cleaner Shrimp Video

34. Parasitism
When one organism, usually physically smaller of the two (the parasite) benefits and the other (the host) is harmed.
+ and - = One species benefits from the interaction and the other is adversely affected. Examples are predation, parasitism, and disease.
Examples???

35. Basic classification of
vertebrates and fishes:
By the way:
Fish – single individual or
more than one individual
of the same species.
Fishes – more than one kind
of fish.