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The first shark-like chondrichthyans appeared in the oceans 400 million years ago, [1] developing into the crown group of sharks by the Early Jurassic. [2] Listed below are extant species of shark. Sharks are spread across 512 described and 23 undescribed species in eight orders. The families and genera within the orders are listed in ...
The use of sight probably varies with species and water conditions. The shark's field of vision can swap between monocular and stereoscopic at any time. [58] A micro-spectrophotometry study of 17 species of sharks found 10 had only rod photoreceptors and no cone cells in their retinas giving them good night vision while making them colorblind.
Large sharks found hooked but still alive are shot and their bodies discarded at sea. [26] The government claims they are not culling sharks, but are using a "targeted, localised, hazard mitigation strategy". [27] Barnett has described opposition to killing the sharks as "ludicrous" and "extreme", and said that nothing can change his mind. [28]
The International Union for the Conservation of Nature reports 35% of all shark species are threatened with extinction. That number has grown nearly 50% in a decade’s time. That number has grown ...
Sharks are split into eight orders: Carcharhiniformes: ground sharks, the largest order of sharks, including requiem sharks, catsharks, swellsharks, houndsharks, weasel sharks and hammerheads; Heterodontiformes: bullhead sharks; Hexanchiformes: cow sharks and frilled sharks; Lamniformes: mackerel sharks, including thresher sharks
Most of the full-time fish – more than half of which are on the IUCN Red List of threatened species – are of the smaller variety. But sharks of great size are not uncommon off these shores ...
One of the first species of shark to be protected was the grey nurse shark. 1992 cageless shark-diving expedition – first publicized cageless dive with great white sharks which contributed to changing public opinions about the supposed "killing machine"
Video above: Tail end of shark week celebrated at Shark Con. TAMPA, Fla. (WFLA) — Researchers have confirmed the existence of a new species of shark in South America.