Marine reptile

Reptiles that live in the sea.
Sea turtle.

Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semi-aquatic life in a marine environment.

The earliest marine reptiles arose in the Permian period during the Paleozoic era. During the Mesozoic era, many groups of reptiles became adapted to life in the seas, including such familiar clades as the ichthyosaurs, plesiosaurs (these two orders were once thought united in the group "Enaliosauria,"[1] a classification now cladistically obsolete), mosasaurs, nothosaurs, placodonts, sea turtles, thalattosaurs and thalattosuchians. After the mass extinction at the end of the Cretaceous period, marine reptiles were less numerous.

Currently, of the approximately 12,000 extant reptile species and sub-species, only about 100 of are classed as marine reptiles: extant marine reptiles include marine iguanas, sea snakes, sea turtles and saltwater crocodiles.[2] The Murua gharial was yet another example of a fully marine reptile, that became extinct rather recently.

Some marine reptiles, such as ichthyosaurs and mosasaurs, rarely ventured onto land and gave birth in the water. Others, such as sea turtles and saltwater crocodiles, return to shore to lay their eggs. Some marine reptiles also occasionally rest and bask on land.

Extant varieties

Conservation

Most species of marine reptiles are considered endangered to some degree. All but one species of sea turtles are endangered due to destruction of nesting habitats on coastal lands, exploitation, and marine fishing;[3] many species of sea snakes are threatened or endangered due to commercial exploitation (sale of skins) and pollution especially in Asia; marine iguanas are threatened due to their very limited habitation range.[2] Saltwater crocodiles are at low risk for extinction.[6]

See also

References

  1. Williston SW (1914) Water Reptiles of the Past and Present University of Chicago Press (reprint 2002). ISBN 1-4021-4677-9
  2. 1 2 3 4 5 6 Rasmussen, Arne Redsted; Murphy, John C.; Ompi, Medy; Gibbons, J. Whitfield; Uetz, Peter (2011-11-08). "Marine Reptiles". PLoS ONE 6 (11): e27373. doi:10.1371/journal.pone.0027373. PMC 3210815. PMID 22087300.
  3. 1 2 Zug, George R. "Sea Turtle". Encyclopedia Britannica Online. Retrieved December 8, 2015.
  4. "Sea Snake". Encyclopedia Britannica Online. Retrieved December 8, 2015.
  5. "Marine Iguanas". National Geographic. Retrieved December 8, 2015.
  6. 1 2 "Saltwater crocodile". National Geographic. Retrieved December 8, 2015.
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