Believe it or not , there is a
species of shark only 30 cms long: the dwarf shark. the next smallest is the cookie-butter
shark, about half a meter long and a parasite of the whale and the porpoise. Its lower jaw boasts an arc of very sharp teeth , which it thrusts into its prey and twists to slice out a mouthful or two of skin and flesh. Cookie- cutters will even attack the rubber sonar-domes on nuclear submarines. in contrast, the whale shark, the largest fish in the sea can touch 20 metres and weight over 10 tonnes. Paradoxically. it presents no menace to human beings but lives on small fish and plankton. The whale shark swims slowly, usually just beneath the surface, running large volumes of water through its mouth to sieve out its tiny prey. Bold swimmers sometimes dive down alongside whale
sharks, take hold of their dorsal fins and hitch a ride.
There are, in fact some 350
species of shark and they differ from one another greatly. There are gulper sharks, bramble sharks, mandarin dogfish, spurdogs, saw-sharks, goblin sharks, pygmy sharks, to mention just a handful. Sharks exhibit the phenomenon termed adaptive radiation. This means that over the course of time, sharks have subdivided into individual species specialised to fil very diverse niches in the ecology. There is a proliferation of such species, and major diversification of this sor frequency produces basic types that cannot be found in any other group.
Right at the bottom of the ocean floor dwell the eel-like frill sharks, with the same kind of jumbosized mouth and razor-sharp teeth that characterise deepsea predatory fish. Way above them cruise the blue sharks, blacktipped sharks and other streamlined species, so beautifully built to pursue their querry and to manoeuvre with ease. On the continental shelves are found angel sharks- sluggish, flat square-bodied creatures and saw sharks, which, with their grostesque snouts lined with outward jutting teeth, are very hard to tell from the true swafish. The thresher shark actually heards fish and squid into small shoals with swift charges and then stuns its victims with strikes of its long whiplike tail. Because of this peculiarity, fishermen usually hook tthreshers in the tail rather than in the mouth.
the tiger shark, otherwise known as the garbage bin of the ocean, can reach 7 metres and weigh a tonne. these sharks often patrol refuse- filled harbours and are attracted to virtually anything that contains animal protein. stomachs of captured specimens have yielded fish, boots, beer, bottles, bags of potatoes, coal, dogs and even part of human beings. One mammoth contained this haul: 3 overcoats, apair of rubber galoshes, a driver's licence, one pig's trotter, the antlers of a deer, a dozen undigested lobsters and a squashed chicken coop complete with feathers and bones. Small wonder that swimmers get grabbed now and then, though nothing personal in intended: the tiger shark is simply a big eater and not hostile to man in particular.
Then there are wobbegongs of the western Pacific. these are club shaped and have fleshy barbels arrayed along their mouths and the sides of their head. They are mottled, a fact that enables them to blend into the ocean floor, for which reason they are also known as carpet sharks. Torpid by nature, the push themselves along the bottom with their pectoral fins. they are dangerous to humans and if stepped on flip around and seize the offender with their piranha- sharp teeth, hanging on with a bulldog grip.
But the ultimate product of all this evolution is the great white shark. this superbly developed predator attacks with ferocious tenacity and has rightfully been called the top carnivore, a sleel killing machine, the last free predator of man, and the most fear-instilling crature in the world. Now we are not just afraid of predators, we are transfixed by them, prone to weave stories and fables and chatter on forever about them, may be because of our fascination engenders readiness and readiness is conducive to survival. the great white shark is a general flesh-eater that consume a huge range of bony fish, other sharks, sea turtles and... This is the key factor...marine mammals such as porpoises, sea-lion and seals. the adult great whit shark is so fond of sea mammals tha this otherwise solitary creatures- the lone wolf of the ocean- is willing to join the pack sometimes and gather close to seal and sea lion rookries, especially around breeding time. The white shark is a threat to people simply because it does not make any distinction between a seal and a human. Afterall, why should it?