Striding leg

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The pereiopods sit on the thoracic segments.
In the amphipods, the front pereiopods can be transformed into gnathopods

A striding leg , also called pereiopod or peraeopod , (from the Greek peraioo = to go over, in English spelling sometimes pereopod ) is a limb on the thoracic segments of the higher crabs .

Derived from the split bone, which was the original for all limbs of the crustaceans, they consist of seven limbs (peraepods) (occasionally only six because of adhesions). These are (from proximal to distal ): coxa and base as well as ischium , merus, carpus, propodus and dactylus of the original endopodite. In the females of some species, remains of the exopodite may also be present at the base.

The crustaceans originally had eight thoracic segments that, together with the head, form the cephalothorax . Most orders usually only have seven pairs of striding legs. Numerous adjustments to individual or all pairs of legs are used for systematic subdivision. These characteristics are often reflected in the scientific names such as Isopoda or Amphipoda .

The function of the pereiopods is different. They are used for swimming or running locomotion as well as for feeding and, in some cases, for defense.

With the decapods (Decapoda) only the limbs of the last five thoracic segments are called striding legs. The foremost of these five pairs of striding legs carries the claws in many groups such as the large crabs and crabs .

The amphipods (amphipods), the first two of the seven Pereiopodenpaare are often trained to Gnathopoden. The end links of these pairs of legs can form claws or claws and can be used for catching or chopping food. The coxes of the striding legs in the amphipods are immobile and form the coxal plates lying on the side of the body.

In the Euphausiacea , the krill, the striding legs form a trap-like catching device with which food is filtered out of the water.

See also

supporting documents

  • Pereiopod in the Crustacea Glossary of the Natural History Museum of Los Angeles County

Individual evidence

  1. ↑ Uwe Werner: Peraeopods. In: Claus Schaefer, Torsten Schröer (Hrsg.): The large lexicon of aquaristics. Eugen Ulmer, Stuttgart 2004, ISBN 3-8001-7497-9 , p. 760.