Great white sharks
Sharks are sensitive to light and can detect objects even in murky water. Some sharks have a mirror like layer under the retina that allows more light into the eye. Sharks do have ears, but the role of hearing in the shark's location of prey is not well understood yet. Sharks have a lateral line, or lateralis system, which helps them detect sound waves and disturbances in the water. This system co[...]DOWNLOAD REFERAT
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Sharks can also sense electricity and magnetic fields. Sensory pores located on the shark's head can detect prey's bioelectric field even if the prey is buried in sand. A shark can also detect the earth's magnetic field. Open-ocean sharks may use this information to navigate and orient themselves.
The great white shark roams in many of the world's seas and oceans. It does however spend most of its time in shallow coastal areas where there is plenty of prey. The great white is found mainly off the coasts of North America, southern Africa, Australia, New Zealand, Japan, and parts of the Mediterranean. Typically the great white avoids very warm or cold seas, and is most comfortable in water about 50-70 degrees F. It has however been known to wander as far north as Alaska.
Sharks unlike most fish must always keep swimming in order to breath. If they stop, they will sink to the bottom and drown. This is because they do not have a swim bladder, which is a small air fill organ. They must keep the water moving across their gills to get oxygen at all times to breathe. « mai multe referate din Biologie