Ants, like all insects, do indeed breathe. Unlike vertebrates they do not
have lungs or an oxygen-carrying blood pigment (like the heme in hemoglobin for
us). Instead they rely on a system of tubes, called tracheae and tracheoles,
which carry atmospheric oxygen to the tissues and almost to the cellular level.
The outside openings of the tracheae are called spiracles. Gas exchange is
primarily by diffusion, although larger active insects my help this along by
contracting and expanding muscles around the tracheae in a process called
ventilation. Ants are small enough that they need only a few spiracles and do
not use ventilation. These openings usually have valves that allow the
spiracle to be open or closed. As noted earlier the blood does not transport
oxygen and is not red as it is in vertebrates.
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