The carapace of a typical cumacean is composed of several fused dorsal head parts and the first three somites of the thorax.

In the genus Campylaspis and a few related genera, the mandibles are transformed into piercing organs, which can be used for predation on foraminiferans and small crustaceans.

[4] Many shallow-water species show a diurnal cycle, with males emerging from the sediment at night and swarming to the surface.

Other differences are the length of the second antenna, the existence of pleopods in males, and the development of a marsupium (brood pouch) in females.

The larvae leave the marsupium in the manca stage, in which they are almost fully grown and are only missing their last pair of pereiopods.

The German zoologist Carl Wilhelm Erich Zimmer studied the order Cumacea very intensively.

[6] Fossil Cumaceans from the early Jurassic scarcely differ from living forms (Bacescu & Petrescu 1999).

Exceptional details such as the gut, mouth parts, pereopods, setae bearing uropods, antenna with developed flagella, and even small eyes with ommatidia were preserved.

Eobodotria straddles a gap of almost 165 million years in the fossil record of sea commas, providing a reliable calibration point for phylogenetic studies.