Turtles, terrapins and tortoises
Turtles, terrapins and tortoises are all in one order, called the Testudines. They all have a shell, though only certain species can withdraw their lead and limbs into it. All the many types of turtle, terrapin and tortoise lay eggs. In some, the temperature at which the egg incubates will decide whether the embryo becomes male or female.
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Family
Cheloniidae
Olive ridley turtles (species)Pelomedusidae
Giant river turtle (species)
Tortoises (Testudinidae)Tortoises inhabit a variety of warm places from deserts to jungles. In the wild, most tortoises have a very short hibernation, as the climate rarely gets too cold.
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About
Turtles are reptiles of the order Testudines (the crown group of the superorder Chelonia), characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield. "Turtle" may either refer to the Testudines as a whole, or to particular Testudines which make up a form taxon that is not monophyletic—see also sea turtle, terrapin, tortoise, and the discussion below.
The order Testudines includes both extant (living) and extinct species. The earliest known turtles date from 215 million years ago, making turtles one of the oldest reptile groups and a more ancient group than lizards and snakes. About 300 species are alive today, and some are highly endangered.
Like other reptiles, turtles are ectotherms—varying their internal temperature according to the ambient environment, commonly called cold-blooded. However, leatherback sea turtle have noticeably higher body temperature than surrounding water because of their high metabolic rate.
Like other amniotes (reptiles, dinosaurs, birds, and mammals), they breathe air and do not lay eggs underwater, although many species live in or around water. The largest turtles are aquatic.
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Scientific Classification
Order: Turtle (Testudines)
Other Reptilia
- Crocodiles, caimans and allies (Crocodilia)
- Lizards, snakes and allies (Squamata)
Elsewhere on the web
- Animal Diversity Web (animaldiversity.ummz.umich.edu)
- Turtle (wikipedia.org)
Site links
BBC links
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