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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 ...
Sharks are found in all seas. They generally do not live in fresh water, with a few exceptions such as the bull shark and the river shark which can swim both in seawater and freshwater. [99] Sharks are common down to depths of 2,000 metres (7,000 ft), and some live even deeper, but they are almost entirely absent below 3,000 metres (10,000 ft).
There are numerous species of sharks found in the Pacific Ocean; of these sharks, 36 [1] have habitat ranges throughout the coastlines and surrounding waters of California, as identified below. Identifications include common names; scientific names; the taxonomic rank, family; conservation statuses according to IUCN; and an image.
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
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
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
"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 ...
The average spinner shark is 2 m (6.6 ft) long and weighs 56 kg (123 lb); this species attains a maximum known length and weight of 3 m (9.8 ft) and 90 kg (200 lb). Indo-Pacific sharks are generally larger than those from the northwest Atlantic. [3] This species has a slim, streamlined body with a distinctive, long, pointed snout.