Turtles are reptiles of the order Chelonii or Testudines characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield. "Turtle" may either refer to the order as a whole, or to particular Turtle which make up a form taxon that is not monophyletic.
The order Chelonii or Testudines includes both extant (living) and extinct species. The earliest known turtles date from 220 million years ago, making turtles one of the oldest reptile groups and a more ancient group than lizards, snakes or crocodiles. Of the many species alive today, some are highly endangered.
Like other reptiles, turtles are ectotherms—their internal temperature varies according to the ambient environment, commonly called cold-blooded. However, leatherback sea turtles 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.
Read more about Turtle: Anatomy and Morphology, Ecology and Life History, Systematics and Evolution, Turtle, Tortoise, or Terrapin, Distribution, Fossil Record, Genomics, As Pets, As Food, Traditional Medicine, and Cosmetics, Conservation Status
Famous quotes containing the word turtle:
“I think of the nestling fallen into the deep grass,
The turtle gasping in the dusty rubble of the highway,
The paralytic stunned in the tub, and the water rising,
All things innocent, hapless, forsaken.”
—Theodore Roethke (19081963)
“My beloved spake, and said unto me, Rise up, my love, my fair one,
and come away.
For lo, the winter is past, the rain is over and gone;
The flowers appear on the earth; the time of the singing of birds is come, and the voice of the turtle is heard in our land;”
—Bible: Hebrew The Song of Solomon (l. II, 1012)
“The second day of Christmas,
My true love sent to me
Two turtle doves,”
—Unknown. The Twelve Days of Christmas (l. 46)