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Rising demands for shark products has increased pressure on shark fisheries, but little monitoring or management occurs of most fisheries. [7] Major declines in shark stocks have been recorded over the past few decades; some species had declined over 90% and population declines of 70% were not unusual by 1998. [8]
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 shark is among the 25 "most wanted lost" species that are the focus of Global Wildlife Conservation's "Search for Lost Species" initiative. [2] The Pondicherry has been spotted in rivers in India in the late 2010s. [3] A Pondicherry shark was caught in the Menik Ganga (river) in SE Sri Lanka in 2011. It was photographed and released alive.
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 ...
The most widely known species still surviving is the frilled shark, known as a living fossil, along with the Southern African frilled shark, found along coastal areas of South Africa. Several extinct species are known. †Crassodontidanidae †Crassodontidanidae: 4 8 Extinct: Hexanchidae: Cow sharks: 3 extant 5 extinct 5 extant 31 extinct
The lost shark (Carcharhinus obsoletus), [a] previously known as the false smalltail shark, is a possibly extinct species of requiem shark (family Carcharhinidae). It is known only from the Western Central Pacific Ocean , in the southern South China Sea .
Squalicorax, commonly known as the crow shark, is a genus of extinct lamniform shark known to have lived during the Cretaceous period. The genus had a global distribution in the Late Cretaceous epoch. Multiple species within this genus are considered to be wastebasket taxon due to morphological similarities in the teeth.