The Structure of Insects
Insects are creatures that are sometimes referred to as “inside out and upside down”.
They are described as inside out because their skeleton is on the outside of the
body, and they are described as upside down because their central nerve cord runs
along the lower (ventral) side of their body, while their heart lies on the upper
(dorsal) side of their body).
Insects differ from us in a number of ways. They do not have lungs, instead they
breathe through a number of tiny holes in the body called spiracles, which lead
into a system of internal tubes called tracheae. Insects have no lips per se. They
see through complex eyes composed of hundreds or even thousands of tiny individual
lenses, or ommatidia. Insect blood does not carry oxygen and simply fills the body
cavity and is circulated by a tube-like heart. Insects see different colors than
we do. They cannot see red but do see ultraviolet light, called “bee purple”. Most
insects cannot hear and none have ears on their head. Insects that can hear use
eardrums in their legs or abdomen, or other modifications of the antennae. They
taste with their tarsi (feet) and smell with their antennae. Insects are cold-blooded,
which means that they have the same body temperature as their environment.