There are four animal groups that fall under the title of reptile; these animals are turtles and tortoises; lizards and snakes, crocodiles and alligators and the tuatara. Reptiles are vertebrates with scaly skin to keep their bodies from drying out. The reptile looks like a miniature version of its adult self when first hatched; cold-blooded animals they have to stay in a warm area to get them warm and active and require a cool area to cool them down. All types of reptiles are born on land.
Turtles and Tortoises
The turtles that live entirely on land are referred to as tortoises. Both turtles and tortoises can be as small as 4.3 inches or as large as eight feet long and weigh over 2,000 pounds. They have shells made from flat bones that are joined with parts of the spinal column and the ribs. Most turtles have there shell bones covered with scutes (broad scales). The shells of those that spend most of their life on land have heavier shells than those that spend more time in the water.
Lizards and Snakes
There are more than 4300 species of lizards making them the most varied and thriving reptile group today. Lizards are normally long and slender tapering to a narrow and pointed tail. The majority have four legs and clawed toes. Ranging in size from one and a half inches to the largest lizard known as the Komodo dragon that is almost ten feet long and weighs in at nearly 365 pounds.
The smaller ones are more agile and eat insects found in trees, shrubs and rocky places. The larger species eat other animals and plants scraping algae from rocks located underwater with their claws and teeth. Only the Gila monster and the beaded lizard have the ability to make venom. There are also 152 species of worm lizards which are related to lizards and snakes and even look like snakes.
There are over 2500 species of snakes; a reptile with no limbs that are closely related to the lizard. A snake can be as little as five inches long or as big as sixty inches long for your average snake. The anaconda is native to South America and a member of the boa family is believed to be the largest a length of up to thirty-three feet and a weigh of up to 550 pounds.
The snake evolved from the lizard but does not have any external ears and transparent scales protect their eyes. The snake can live in most any environment on the earth. While most are harmless there are some that are deadly; the viper, rattlesnake and cobras are the most known of these although the colubrids contain some venomous varieties within the group.
Crocodilians (Alligators and crocodiles)
Normally ranging from six to thirteen feet but some varieties can grow as large as thirty-three feet and weigh over a ton. While the crocodile will usually live in warm tropical climates, the alligator usually prefers a more temperate climate like the one found in the southern portion of the United States. Crocodilians will spend the majority of time in the water and are graceful swimmers that use their tails to swim with. The eyes and nostrils are on top of the head and show about the water while they glide through it.
Tuatara
The tuatara (living fossil) has two species of its own and is the only surviving members of a reptile group that first appeared over 200 million years ago. The tuatara is similar to the lizard but it has differences in the skeleton and other parts of the body. The tuatara is only found in New Zealand today. It can be anywhere from eighteen inches to twenty-four inches long. They grow slowly and take their time in developing. They will grow until the age of thirty five and are believed to live for over a hundred years.
Sources:
http://www.sandiegozoo.org/animalbytes/a-reptiles.html
http://encarta.msn.com/encyclopedia_761579044/reptile.html
http://www.auburn.edu/academic/education/reading_genie/chall/jonesrl.html
