Members of the family Mysidae can be distinguished from other mysids by several key characteristics. First, the first pereopod, or walking leg, is equipped with a well-developed exopod, which is an outer branch. Additionally, the carpopropodus of the endopod, which is the inner branch, of the 3rd to 8th pereopods is divided into sub-segments, giving them a segmented appearance. Another distinguishing feature in Mysidae is the presence of statocysts on the endopod of the uropods, which are the posterior appendages. In female petalophthalmidans, there are typically two or three oostegites, which are flexible and bristly flaps. These oostegites form the base of the marsupium or brood pouch located under the thorax.