Turtle
This article is about the animal. For all other uses see Turtle (disambiguation).\n----\n
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Sea Turtle |
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Turtles, a generic name for the group of
reptiles which includes
tortoises and
terrapins, are reptiles most of whose body is shielded by a special bony shell developed from their ribs. All extant, or living, turtles are members of the order
Testudines, which includes both living and
extinct varieties of turtle.
There are two major groups of turtles: sea turtles, which grow to large sizes and live in the oceans in the temperate and
tropical regions of the earth, and fresh-water turtles.
Fresh-water turtles which spend the majority of their time on the land are generally called tortoises. In the
United Kingdom aquatic fresh-water turtles are known as terrapins. Fresh-water turtles are generally much smaller, ranging in size from a few centimeters to a few feet long. All turtles have a protective shell around their bodies. The top part of their case is called the
carapace, the underside is the
plastron, and the two are connected by the bridge.
The size of turtles can vary from a few centimetres to up to two meters. Turtles generally live a long time; some individuals are known to have lived longer than 150 years.
The first turtles already existed in the era of the
dinosaurs, some 200 million years ago. Turtles are the only surviving branch of the even more ancient
clade Anapsida, which includes groups such as the procolophonoids, millerettids and pareiasaurs. All anapsid skulls lack a temporal opening. All other extant amniotes have temporal openings (although in
mammals the hole is obscured). Most of the anapsids became extinct in the late
Permian period, with the exception of the procolophonoids and the precursors of the testudines (turtles).
Even though they spend large amounts of their lives underwater, turtles are air-breathing reptiles, and must surface at regular intervals to refill their lungs with fresh air. They also spend part of their lives on dry land. Sea turtles lay their eggs on dry sandy beaches, and are highly endangered largely as a result of beach development and over hunting.
Aquatic respiration in Australian freshwater turtles is currently being studied. Some species have large cloacal cavities that are lined with many finger-like projections. These projections, called "papillae", have a rich blood supply, and serve to increase the surface area of the cloaca. The turtles can take up dissolved oxygen from the water using these papillae, in much the same way that fish use gills to respire.
\nA sea turtle. Photo credit:
NOAA
Order Testudines - Turtles
Suborder Cryptodira\n*Family Chelydridae (Snapping Turtles)\n*Superfamily Testudinoidea\n*Family Testudinidae (Tortoises)\n*Family Bataguridae (Asian River Turtles, Leaf and Roofed Turtles, Asian Box Turtles)\n*Family Emydidae (Pond Turtles/Box and Water Turtles)
Suborder Pleurodira\n*Family
Chelidae (Austro-American Sideneck Turtles)
- Superfamily Pelomedusoidea\n*Family Pelomedusidae (Afro-American Sideneck Turtles)\n*Family Podocnemididae (Madagascan Big-headed and American Sideneck River Turtles)
Turtles in pop culture
The Teenage Mutant Ninja Turtles are comic characters.
In the song
Abcdefghijklmnopqrstuvwxyz,
Sesame Street character
Big Bird ponders if Abcdefghijklmnopqrstuvwxyz is a "Or strange, exotic turtle/You never see in a zoo".
Terry Pratchett's
Discworld rests on the back of the gigantic star-turtle
Great A'Tuin.
See also
\n*Predator\n*
Jackson ratio
External links
\n* The Turtle Pages\n*
UC Berkeley Museum of Paleontology\n*
Bimodally-breathing Turtle research\n*
Turtle Trax: Excellent marine turtle site\n*
California Turtle and Tortoise Club: Informative and entertaining in equal measure\n* (Unrelated porn link removed)\n*
Turtle Times: A turtle search engine!
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