Minggu, 26 Agustus 2012



The Biggest Animals Kingdom and in The World | Shark | Shark teeth are embedded in the rubber are not directly attached to the jaw, and continually replaced throughout life. Before the simultaneous replacement of a large number, which is observed in the cutter shark Tooth shape depends on the diet of sharks: They feed on mollusks and crustaceans, a dense and flattened teeth are used for crushing, which feed on fish have needle-like teeth for gripping, and those who are lower on larger prey such as mammals teeth to gripping and triangular upper teeth with serrated edges for cutting showed. The teeth of plankton-feeders such as the basking shark are small and non-functional Shark skeletons are very different from those of bony fish and terrestrial vertebrates. Sharks and other cartilaginous fish (skates and rays) have skeletons of cartilage and connective tissue. Rib cages because no sharks, they can easily under their own weight landJaws of sharks, rays are not as, are attached to the skull crushed. 

Generally sharks have only one layer of tesserae, but the jaws of large specimens, such as the bull shark, tiger shark and the great white shark, two to three layers or more, depending on body size. The jaws of a great white shark can be up to five layers. Most sharks have eight fins. Sharks only drift away from objects directly in front of them because they do not move their fins allow the tail-first directionUnlike bony fish, sharks have a complex dermal corset made of flexible collagenous fibers and arranged as a helical spring surrounding body network. Caudal fin shapes vary considerably between the types of sharks, as a result of evolution in separate environments. Sharks have a heterocercal caudal fin in which the dorsal portion is usually noticeably larger than the ventral. Since the shark dorsal spine is in the part, so that.

Other adaptations help sharks tail to catch prey more directly, such as the use of the thresher shark from its powerful, elongated upper lobe stun fish and squid. Some species, such as nurse sharks, have external barbels that greatly increase their ability to sense prey to. Visibility in the dark water The effectiveness of the tissue varies, with a stronger sharks night adjustments. Sharks have eyelids, but do not blink because the surrounding water cleans their eyes. To protect their eyes some species nictitating membranes. This membrane covers the eyes while hunting and when the shark attacked. The importance of eyes in shark hunting behavior is discussed. Presumably, the shark not to protect their eyes, they were unimportant. The shark vision can change between monocular and stereoscopic at any time. A micro-spectrophotometry study of 17 species of sharks found 10 only rods and no cones in their retinas were them good night vision and makes them color blind.

Sharks seen with the ampoules Lorenzini on the electromagnetic fields that all living things produce. This helps sharks (particularly the hammerhead shark) find prey. The shark has the greatest electrical sensitivity of an animal. Sharks find prey in the sand by detecting the electric fields they produce hidden. Ocean currents moving in the magnetic field of the earth and electric fields that sharks selected for orientation and possibly use navigationUnlike most bony fishes generate sharks K for the show, giving them developed a small number of well-developed young production as opposed to a large number of poor young . Fertility in sharks ranges from 2 to over 100 young per reproductive cycle. Sharks mature slowly relative to many other fish. For example, lemon sharks reach sexual maturity around the age of 13-15.

Shark migration patterns may be even more complex than in birds, with many sharks entire ocean basins. Sharks can be highly social, even in large schools. Cross-species social hierarchies exist. For example, white tip dominate silky sharks of comparable size during feeding. To close when some sharks perform a threat display. This usually consists of exaggerated swimming movements, and can vary in intensity depending on the threat level In general, sharks ("cruise") swim at an average speed of 8 kilometers per hour (5.0 mph) but when feeding or attacking, the average shark speeds can reach upwards of 19 kilometers per hour (12 mph) .

The shortfin mako shark, the fastest shark and one of the fastest fish, can burst at speeds up to 50 kilometers per hour (31 mph). The great white shark is also capable of speed bursts. These exceptions may be due to the warm-blooded or homeothermic, nature of these sharks physiology. Sharks are found in all seas. They generally do not live in freshwater, with a few exceptions such as the bull shark and the river shark which can swim both in seawater and freshwater. The deepest confirmed report of a shark is a Portuguese dogfish at 3,700 meters (12,100 ft).

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