Monstrillidae

Monstrilloida is an order of copepods with a cosmopolitan distribution in the world's oceans. The order contains a single family, Monstrillidae. The name of the first ever described genus Monstrilla is derived from Latin, meaning "tiny monster", because the lack of usual diagnostic features of copepods puzzled early taxonomists.

== Description == The family Monstrillidae is characterised by having a well-developed fourth pair of swimming legs, but a rudimentary or absent fifth pair. Adults have no oral appendages, and the mouth leads only to a short, blind pharynx. They also lack second antennae, but show large, multiramous and setaceous antennulae. These antennulae are rigid and anteriorly oriented. Females carry a long pair of spines to which the eggs are attached, while males have a "genital protuberance, which is provided with lappets"; in both sexes, the genitalia are very different from those of all other copepods. Some species have large, well-developed nauplius eyes, while others are basically blind.