Reptiles are (typically) scaled, cold-blooded creatures. There are four or five main known types of reptile, depending on the definition:
Snakes, who are identified by their lack of ears, legs, and eyelids;
Lizards, who are snakes but with eyelids and legs and earholes;
Turtles, or the reptiles with shells;
Tuatara, a species that looks like a lizard but really is not;
and Crocodilians, which is sort of it's own thing but gets grouped with reptiles because they look like lizards.
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