Chapter three: Turtles
Turtles are reptiles of the order Chelonii or Testudines characterised by a special bony or cartilaginous shell developed from their ribs and acting as a shield.Turtle may refer to the chelonian order as a whole (American English) or to fresh-water and sea-dwelling chelonians (British English).[4]
The order Chelonii or Testudines includes both extant (living) and extinct species. The earliest known turtles date from 220 million years ago,[5] 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 highlyendangered.[6]
Like all other extant reptiles, turtles are ectotherms—their internal temperature varies according to the ambient environment, commonly called cold-blooded. However, because of their high metabolic rate, leatherback sea turtles have a body temperature that is noticeably higher than that of the surrounding water.
Turtles are classified as amniotes, along with reptiles, dinosaurs (including birds), and mammals. Like other amniotes, turtles breathe air and do not layeggs underwater, although many species live in or around water.
Turtles are divided into two groups, according to how they evolved a solution to the problem of withdrawing their necks into their shells (something the ancestral Proganochelys could not do): the Cryptodira, which can draw their necks in while contracting it under their spine; and the Pleurodira, which contract their necks to the side.
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Sea Animals
Science FictionThe sotry is about sea animals that tell us if they are extinct endangerd or rare what type of animal it is and to what type of spiece it is what it eat and where it eat when it eat and how it eat.
