Leptostraca

Nebalia bipes

The Leptostraca are an order of Major crabs ( Malacostraca ). They are the only living order of the subclass Phyllocarida. Two other orders that Archaeostraca and Hoplostraca are extinct.

System

The systematic position of the Phyllocarida has long been controversial. The crustacean specialist Henri Milne Edwards, it placed because of their two-part carapace the Kiemenfußkrebsen ( Branchiopoda ). Only after they had studied the embryonic development of Phyllocarida, which coincides with the higher crustaceans, and had discovered Chiltinleisten in the gizzard presented to them to the Malacostraca.

There are about 20 species, belongs to the families of the Nebaliopsidae and Paranebaliidae one type each. The rest belong to the Nebaliidae.

Anatomy

The carapace of Leptostraca is only connected to the head. The team of eight segments in the thorax can be moved freely. At the anterior end of the carapace is a movable rostral under which the sitting on stalks compound eyes sit on both sides. There is a brush-like, rear-facing institution with which the carapace inside and the thorax can be agreed on the maxillae. The Leptostraca have two ungefiederte sensor pairs that are worn down and back. At the end of the thorax is a continuously tapering and existing of seven segments caudal peduncle joins.

Way of life

Most Leptostraca live on the ocean floor, from the coast to depths of 400 meters, and seven of their existing food detritus from the soft sludge. Nebaliopsis typica, only species of the bathypelagic Nebaliopsidae family lives in warm seas. Two other species live in the deep sea.