Snakes are typically carnivorous, and many of them are furnished with
powerful poison fangs. The tongue is forked, can be rapidly protruded
and retracted, and is an efficient sense organ. Upon it and the
well-developed nostrils the snakes largely depend, for neither sight nor
hearing is very acute. There are no eyelids, the eyes being covered over
by a transparent convex scale. The whole skin is covered with scales,
which are folds of the epidermis, continuous with one another. In
consequence, when the snake casts its coat--which occurs several times
in the year--it casts it in one piece, this being a complete replica of
the snake.