Dendrogastrida Grygier, 1987 Laurida Grygier, 1987 Ascothoracida is a small group of parasitic marine crustaceans, comprising around 100 species and divided into Dendrogastrida and Laurida.

Piercing and sucking mouthparts are used for feeding, and more advanced forms also absorb nutrients through a modified integument of the carapace.

The sexes are separate, except from secondary hermaphroditic species of the Petrarcidae.

In many species the larger female often have smaller males living inside her mantle cavity.

[2][7][8] The thorax of Ascothoracida species has six pair of biramous appendages, while the abdomen has four segments and a terminal telson with a caudal furca.