1 Class: Osteichthyes - Bony Fish As Chordates, fish have an incredible variety of characteristics. Most are covered with flat scales that fit into pockets in the skin and have a mucus coating. Some lack scales or have tiny scales. Some can be reabsorbed if food is scarce. Scales contain chromatophores that cause color changes for camouflage, mating - species recognition or when stressed. Marlin Photo by Betty Newton

2 false eye Cryptic coloration: false eye on butterfly fish; counter-shading, (dark on dorsal surface and light on ventral); camouflage; aid in survival Circulation: 2 chambered heart, most ectothermic Tuna, barracuda and a few others maintain temperature higher (~10 o ) than environment so technically they are endothermic.

3 Respiration: Water containing 0 2 flows over the gills in a different direction than blood so diffusion is maximized; muscles pump water through gills Gases from the blood and/or gulped air are used to adjust buoyancy in the swim bladder. Several gill arches supporting gill rakers and gill filaments are covered by a flap called the operculum. Gills help regulate the salt/water balance called osmoregulation. NOAA

4 Vision: Poor to medium and usually only lateral. Some fish can detect and generate weak electrical currents. This electro-perception is used to communicate in schooling, aids in migration, detecting and stunning prey.

5 Hearing: Aided by the lateral line, the swim bladder and the otoliths (located in the inner ear) detect movements and affect balance. Smell: Chemoreceptors are found on the mouth, lips, skin and fins. Most of brain is olfactory lobes use for smell to find food.

6 Reproduction: sexual, mostly external fertilization called spawning Gonads - sac contains either sperm or eggs (roe). Sex reversal is common in reef fish

7 The red blood cell count in tuna is equal to mammals. Bluefin tuna and sailfish are the fastest fish at nearly at 70 mph.

8 Tuna are exquisitely designed for speed and can swim at 45 mph for long periods. They have a foldable dorsal fin that fits into a groove making it flush with the body to reduce drag when maneuvering. NOAA

9 The largest bony fish is the Mola Mola (Sunfish). Molas eat plankton and can weigh 3000 pounds. They swim slowly and do not have a fusiform body shape, although it can be 11 ft. long.

HUMAN IMPACTS Overfishing – results when catches are higher than the maximum sustainable yield, or optimal catch, of a fishery - with time catches dwindle, fish caught are smaller For a sustainable yield, the number of fish caught must be no more than the number of new fish added through reproduction 10