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The
telson is the last division of the body of a
crustacean. It is not considered a true
segment because it does not arise in the embryo from
teloblast areas as do real segments. It never carries any
appendages, but a forked "tail" called the caudal furca is often present. Together with the
uropods, the
telson forms the
tail fan of
lobsters,
shrimp and other
decapods. These are used as a paddle in the
caridoid escape reaction ("lobstering"), whereby an alarmed animal rapidly flexes its tail, causing it to dart backwards.
Krill can reach speeds of over 60 cm per second by this means. The
trigger time to optical
stimulus is, in spite of the low temperatures, only 55
ms.
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