Kamis, 04 Februari 2010

Shark-Superorder-Selachimorpha






I know this Shark or superorder-Selachimorpha is a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs. It is very big although there are smaller. Sharks have diversified into 440 species, ranging in size from the small dwarf lanternshark, Etmopterus perryi, a deep sea species of only 17 centimetres (7 in) in length, to the whale shark, Rhincodon typus, the largest fish, which reaches approximately 12 metres (39 ft) and which feeds only on plankton, squid, and small fish through filter feeding. Sharks are found in all seas and are common down to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater, with a few exceptions such as the bull shark and the river shark which can live both in seawater and freshwater.
Sharks respire with the use of five to seven gill slits. Sharks have a covering of dermal denticles that protect their skin from damage and parasites and improve fluid dynamics so the shark can move faster. They have several sets of replaceable teeth. They can eat human being if they are hungry and most of them think that human is their eat like sea-dog.
According to me, this shark is not bad because they have not good brain like us. Just avoid them and take care yourself from them. Don't play with them because if they are hungry they can eat you. This is the habitat of shark.