Typical amphipod showing the main divisions of the
body: head (red), thorax (yellow), and abdomen (brown). The first
two pairs of thoracic legs (purple), the gnathopods, assist feeding
and are used by males during copulation. The first three pairs of
abdominal legs (blue) create a water current which aerates the gills
for respiration, and provide the main propulsive force in swimming.
The rear three abdominal appendages are known as uropods, and two
of these (blue) are usually modified to act as rudders.
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