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Sedentary, bottom-dwelling sharks generally use buccal pumping to move water over to their gills compared to more active sharks, who will use ram ventilation and swim to force water to their mouth and gills. Most sharks can switch between these mechanisms as the situation requires depending on the abundance of oxygen in the water.
The sharks are used for their fins and meat. [1] [6] It is eaten fresh, smoked, dried, and salted and its skin made into leather. [6] Bycatching of oceanic whitetip sharks may be reduced by removing hooks from longliners when they are in shallow water. [36] Sharks may also be threatened by pollution.
Many sharks can contract and dilate their pupils, like humans, something no teleost fish can do. Sharks have eyelids, but they do not blink because the surrounding water cleans their eyes. To protect their eyes some species have nictitating membranes. This membrane covers the eyes while hunting and when the shark is being attacked.
In many species of sharks and all rays the spiracle is responsible for the intake of water into the buccal space before being expelled from the gills. The spiracle is often located towards the top of the animal allowing breathing even while the animal is mostly buried under sediments. [ 5 ]
If you’re heading to the beach sometime soon, here are some things to keep in mind about shark attacks — including just how unlikely they really are.
Why do sharks attack humans? According to the Shark Research Institute, there are over 400 plus species of shark around the world, which include great white sharks, tiger sharks and bull sharks.
Ordinarily, spinner sharks do not pose a substantial danger to humans; they do not perceive large mammals as prey, as their small, narrow teeth are adapted for grasping rather than cutting. However, they can become excited by the presence of food, so caution is warranted if this species is encountered while spearfishing . [ 2 ]
Most of the sharks spotted in the area are juveniles — despite their size, the great whites are only up to about 6 years old and very inexperienced hunters.