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The  Habitat of sharks are the oceans, although several species are also found in rivers. Present in all ocean and river regions except in extreme ocean depths, sharks have adapted very well to all of these environments. more
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The Evolution of sharks began more than 400 million years ago when the evolutionary lines of sharks and fish separated. Since that time sharks have developed into hunters who are optimally adapted to their habitat and way of life more
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Several Features differentiate sharks from bony fish. Besides the fact that no two sharks are alike, they have also adapted their appearance to their myriad habitats and environmental conditions. Incidentally, most sharks are too small to be of any threat to humans. The surest way of identifying them are their five to seven gill slits more
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The Anatomy anatomy of sharks exhibits several distinctive features. Contrary to bony fish, their skeleton is made of cartilage instead of bones. They have a valvular intestine (spiral valve) and use their liver like a swim bladder more
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Sharks have seven Senses and some (e.g. night vision and the sense of smell) are substantially finer than the respective senses of many mammals. For example, sharks can see better in the dark than cats.
The shark's most astounding sense is its electrosense. Using their ampullae of Lorenzini they can detect even very fine currents, such as those emanating from a heartbeat more
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The Reproduction of sharks is complex. They reproduce in two ways. Some species bear their pups alive (viviparity) and others lay eggs (oviparity). Those who bear live offspring have developed highly complex forms of feeding their brood. Several species have developed a form of placenta. Only 30% of all sharks lay eggs whose form varies considerably more
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