Search results
Results From The WOW.Com Content Network
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 ...
The broadnose sevengill shark (Notorynchus cepedianus) is the only extant member of the genus Notorynchus, in the family Hexanchidae. 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 ...
In sharks, the ampullae of Lorenzini are electroreceptor organs. They number in the hundreds to thousands. Sharks use the ampullae of Lorenzini to detect the electromagnetic fields that all living things produce. [25] This helps sharks (particularly the hammerhead shark) find prey. The shark has the greatest electrical sensitivity of any animal.
Younger and smaller individuals may be eaten by larger sharks, such as the great white shark and the tiger shark. Orcas have been reported to hunt blue sharks. [5] This shark may host several species of parasites. For example, the blue shark is a definitive host of the tetraphyllidean tapeworm, Pelichnibothrium speciosum (Prionacestus bipartitus).
So far this year, there have been 46 publicly reported shark attacks, seven of which were fatal, according to TrackingSharks.com. And so, the question remains - why do sharks attack humans? Here ...
The sharpnose sevengill shark is reasonably small and is located in generally deep water, and these characteristics classify this shark as harmless to humans. [3] Small to moderate numbers of sharpnose sevengill sharks are captured as bycatch in certain deepwater commercial fisheries on longlines or in trawls . [ 2 ]
The great white shark is one of only four kinds of shark that have been involved in a significant number of fatal unprovoked attacks on humans. Many bite incidents occur in waters with low visibility or other situations which impair the shark's senses. The species appears to not like the taste of humans, or at least finds the taste unfamiliar.