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Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha [1] (or Selachii) and are the sister group to the Batoidea (rays and kin).
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 following outline is provided as an overview of and topical guide to sharks: Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 440 million years ago, before the time of the dinosaurs. [1]
Greenland sharks have also been found with remains of moose, polar bear, horse, and reindeer (in one case an entire reindeer body) in their stomachs. [26] [27] [28] The Greenland shark is known to be a scavenger and is attracted by the smell of rotting meat in the water. The sharks have frequently been observed gathering around fishing boats. [26]
Sand sharks are not known to attack humans. If a person were to provoke a sand shark, it may retaliate defensively. Sand sharks are generally not aggressive, but harass divers who are spearfishing. In North America, wreck divers regularly visit the World War II shipwrecks to dive with the sharks that make the wrecks their home. [8]
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.
There is a reason why movie makers used a great white shark as the shark in the movie Jaws. These massive creatures are the largest predatory fish in the world and routinely hunt large mammals ...
During 10 days of research in 2022 and 2023, the scientists fished for sharks from boats and from shore, using both dropline and more traditional rod-and-reel fishing setups. They caught, tagged ...