Basic Fish Stuff

1. Basic Fish Stuff What is a fish? Most numerous and diverse of major vertebrate groups Over 28,000 of living species so far Occupying vast array of habitats with Temps ranging from �1.8o C to 40o C pH ranging from 4 to 10 DO levels ranging from almost zero to full saturation Salinity from 0 to 99 ppt Huge diversity reflects long evolutionary history

3. Taxonomy cont. Class Chondrichthyes Subclass Elasmobranchii (all sharks, skates, and rays) Subclass Holocephali (chimeras)

4. Taxonomy cont. Subclass Elasmobranchii Superorders Galea wobbegongs, nurse sharks, whale sharks also includes �typical� sharks such as white, thresher, sand tiger,reef, etc. Squalea cowsharks, sleeper, dogfish, angel Batoidea (skates and rays) Order Rajiformes (guitarfish and skates) Order Myliobatiformes (most rays)

5. Taxonomy cont. Bony (Class Osteichthyes) Subclass Sarcopterygii Lobe-finned fishes and terrestrial vertebrates Lungfishes, coelacanths Subclass Actinopterygii Ray-finned fishes Huge diversity in this group

6. Fish Diversity By volume 97% of all water is marine 58% of fish species are marine, 41% are fresh water Mainly due to speciation in response to isolation (ponds, lakes, rivers) Close to 80% of all marine species live in water along coastlines less than 200 m deep

7. Characteristics of water influencing fish design Most fish are recognizable as fish due to the physical and chemical constraints placed on these animals by water Density Low compressibility Universal solvent

8. Density of Water 800 times more dense than air Fish easily remain suspended in water column Most muscular effort is devoted to movement with little being wasted counteracting gravity More thrust can be generated by pushing against water Harder to move through, however, so must be streamlined

9. Low compressibility of water Disadvantages to fish Movement through water is difficult due to its density and low compressibility Water has to be pushed completely out of the way Advantages Lateral line system can detect minute amounts of turbulence and water displacement Slight compressibility allows sound waves to be carried farther and faster than in air Most fish have excellent sense of hearing (through otoliths and gas bladders)

10. Water as a solvent Marine and fresh waters contain mixtures of dissolved gasses, salts, and organic compounds needed by fish to survive. These are taken up directly through gills or indirectly through diet Fish need to expose a large gill surface area to the water to take in oxygen and to eliminate waste products (main reason all fish are cold-blooded)

11. Low permeability to light Most fish found in photic zone High concentration of algae and aquatic plants Majority of fish rely on sight to capture prey, however, many have specialized sensory structures such as barbels, and electric organs

12. Diversity of Body Plan

13. Diversity of Body Plan

14. Diversity of Body Plan

15. Common Body Plan Descriptors

16. External anatomy

17. External anatomy