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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.
[citation needed] Most shark species have five gill slits on each side, however, some species can have up to six or seven like the sixgill sawshark and sharks in the order Hexanchiformes. [40] As part of their respiratory system, sharks also have an accessory respiratory opening called a spiracle behind their eyes. Spiracles are cartilaginous ...
It is recognizable because of its seven gill slits, while most shark species have five gill slits, with the exception of the members of the order Hexanchiformes and the sixgill sawshark. This shark has a large, thick body, with a broad head and blunt snout. The top jaw has jagged, cusped teeth and the bottom jaw has comb-shaped teeth.
The five senses that blue sharks share with other members of the Carcharhinidae family is vision, hearing, lateral line, chemoreception, and electroreception. These senses allow them to perceive and react to a variety of biotic and/or abiotic stimuli in their immediate environment and across a different range of spatial scales. [15]
Horn sharks are innocuous towards humans. Under normal circumstances, horn sharks are harmless to humans and can readily be approached underwater. [3] However, they can be provoked into biting, and some pugnacious individuals have been known to chase and bite divers after being harassed. [6]
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 ...
Sharks do not have moveable upper or lower eyelids, but the tiger shark—among other sharks—has a nictitating membrane, which is a clear eyelid that can cover the eye. [32] A reflective layer behind the tiger shark's retina, called the tapetum lucidum, allows light-sensing cells a second chance to capture photons of visible light. This ...
[10] [11] Juvenile sharks need a higher intake of carbon than adults sharks, especially during the wet seasons. White spotted bamboo sharks have an advantage in finding carbon sources because they are benthic predators (meaning they prey on fish near the sea-bottom), as opposed to pelagic sharks like the spadenose shark.