Tanaidacea

Tanaissus lilljeborgi from the North Sea

As scissors isopods ( Tanaidacea ) an order assel -like crustaceans is called, with about 940 species worldwide live in 224 genera mostly in the substrate of the littoral of the seas, but also in the deep sea and in fresh water.

The animals have a cylindrical articulated body. A carapace covers the first two segments of the thorax. On the first pair of legs sit scissors. A part of the further pair of legs is used to filter the food out of the water. Eyes are on stalks or are not present. They are usually small, and reach only 1 to 2 millimeters in length. The largest species are 20 millimeters long.