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Pleopods

Pleopods are paired, usually biramous abdominal appendages found on many crustaceans, including decapods (shrimp, lobsters, crayfish), krill, and isopods and amphipods. They arise from the abdominal segments (pleomeres) and are typically located on the ventral side of the abdomen. Most species possess several pairs (often five in decapods), though the exact number and structure varies by taxon. Pleopods are frequently flattened and setose, with a proximal endopod and a distal exopod, enabling a broad, lamellate surface that aids respiration. In many swimming crustaceans, pleopods beat in a coordinated manner to generate water currents that propel the animal backwards or forwards, depending on the wave, contributing to locomotion and, in some groups, to swimming efficiency.

In addition to locomotion, pleopods play a key role in respiration by increasing the surface area for

The morphology of pleopods is highly variable. In krill, pleopods are large and are the primary means

gas
exchange
when
immersed
in
water.
In
many
females,
pleopods
support
brood
care:
eggs
are
attached
to
the
pleopods
and
aerated
by
the
water
current
produced
by
their
movement.
of
propulsion;
in
amphipods
and
isopods
they
are
often
leaf-like
and
contribute
to
both
swimming
and
respiration.
The
structure
and
function
of
pleopods
reflect
the
ecological
and
behavioral
demands
of
each
group.