Insects are found throughout the world except on the
poles. Fossil records indicate that many species exist
today in much the same form as they did 200 million
years ago. Their enormous biological success is
attributed to their small size, and the remarkable
adaptive abilities of the group as a whole, shown by the
enormous variety in body structure and way of life. The
mouth parts may be adapted to chewing, sucking or
lapping and the legs for running, jumping or swimming.
Insects may feed on plants or prey upon other small
animals or parasitize larger ones; they may be
omnivorous or highly specialized in their diets. They
display a remarkable variety of adaptive shapes and
colours that may serve either as camouflage or as
warning. So me have stinging spines or hairs and
blistering or noxious secretions, used for defense.