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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.
Freshwater sharks are sharks that live in freshwater environments. While the majority of sharks are solely marine, a small number of shark species have adapted to live in freshwater. The bull shark, Carcharhinus leucas, can swim between salt and fresh water, and
Bodies of water in which sharks can be found include: Seas: all; Freshwater – some species of shark can live both in seawater and freshwater, and include: Bull shark; River shark; Sandbar shark; Depths: from the surface down to depths of 2,000 metres (6,600 ft). A whale shark in the Georgia Aquarium
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
"We have to think about it in terms of the food web that's out in the ocean: Ultimately, at the very top of that cycle of life are the sharks and if we removed the sharks, smaller fish species ...
Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many
Sharks have been made villains in most stories, whether it’s fact or fiction. But as the planet’s climate and oceans rapidly change, these boneless, aquatic, apex predators are also ...