Sharks

12 Pages 2884 Words

) (Gold and Springer 1989). They are found in all seas, but are most abundant in warm waters. The body shapes of sharks vary considerably but there are some similar features between them; they have a streamlined body, shaped like a tornado. This enables them to glide easily through water. In color, most of them are counter shaded to the environment around them. Counter shading is when the dorsal side is darker than the ventral side. Darker coloration on top makes it more difficult to be seen from above while lighter color underneath blends in with the lighter surface of the sea when from below (MML 2003). They are predators of the ocean armed with complex adaptations of teeth, jaws, skin and sensory systems. They can see, hear, smell, navigate and detect even hidden prey. Unlike the bony fishes that rely on external fertilization (the female ejects thousands of small eggs to be fertilized outside the body by males), all sharks accomplish this by internal fertilization. The process of internal fertilization involves highly developed internal and external reproductive organs. They are powerful swimmers and in the wild, some of them may even life up to half a century (Taylor and Taylor 1986).

Sensory Systems: Mechanical and Acoustic Senses
The senses of touch and hearing in sharks involve stimulation of specialized hair like cells located at, or very near, the body surface. Most of the hair cells of sharks occur in grooves, pits or canals which make up a lateral line, extending along the shark’s side and branching throughout the head (Allen 1999). The strain on one of these sensory cells produces an electrical charge, which stimulates an attached nerve fiber and passes the “information” to the shark’s central nervous system. Scientists have found that the lateral line nerves show that the hair cells detect the direction as well as the amount of movement in their fine projections. In other words if the smaller ...