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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 556 described and 23 undescribed species in eight orders. The families and genera within the orders are listed in ...
Sharkbook is a global database for identifying and tracking sharks, particularly whale sharks, using uploaded photos and videos.In addition to identifying and tracking sharks, the site allows people to "adopt a shark" and get updates on specific animals.
In most oviparous shark species, an egg case with the consistency of leather protects the developing embryo(s). These cases may be corkscrewed into crevices for protection. The egg case is commonly called a mermaid's purse. Oviparous sharks include the horn shark, catshark, Port Jackson shark, and swellshark. [80] [82]
The species faces numerous ecological challenges which has resulted in international protection. The International Union for Conservation of Nature lists the great white shark as a vulnerable species, [1] and it is included in Appendix II of CITES. [12] It is also protected by several national governments, such as Australia (as of 2018). [13]
The horn shark (Heterodontus francisci) is a species of bullhead shark, in the family Heterodontidae. ... Photos of Horn shark on Sealife Collection
The bonnethead (Sphyrna tiburo), also called a bonnet shark or shovelhead, [3] is a small member of the hammerhead shark genus Sphyrna, and part of the family Sphyrnidae.It is an abundant species in the littoral zone of the North Atlantic and the Gulf of Mexico, is the only shark species known to display sexual dimorphism in the morphology of the head, and is the only shark species known to be ...
Shark research is hard to get funding for, in part, because sharks aren’t a commercial species. Yet the irony is that they affect commercial species, namely fish populations.
The sandbar shark (Carcharhinus plumbeus), also known as the brown shark or thickskin shark, is a species of requiem shark, and part of the family Carcharhinidae, native to the Atlantic Ocean and the Indo-Pacific. It is distinguishable by its very high first dorsal fin and interdorsal ridge. [2]