Fairy prion

Description

Chirocephalus diaphanus is a "beautiful,translucent crustacean".Its body is subcylindrical,and around 0.5 inches (13 mm) long,mostly transparent,but with black eyes,and red tips to the appendages and abdomen.The body becomes wider towards the head,which has a conspicuous mandibular groove.It also bears a pair of stalked compound eyes,as well as a sessile median eye,two pairs of antennae,and the mouthparts.The mouthparts comprise a labrum,directed backwards over the mouth and pairs of mandibles,paragnatha,maxillules and vestigial maxillae.The thorax is made up of twelve body segments,the last of which is fused to the first segment of the abdomen.There is no carapace,but each of the eleven free segments bears a pair of phyllopodia,which have a series of bristles pointing along the animal's midline.The abdomen consists of seven segments without appendages,and a slender telson which bears a pair of caudal rami.Males and females can be recognised by a suite of sexually dimorphic characters.While the antennae of females are triangular and relatively short,males' antennae are long and jointed,and each one bears a complex "frontal appendage",which is used to clasp the female during mating.The last somite of the thorax is fused with the first somite of the abdomen.In males,it bears a pair of processes,the extensions of the vasa deferentia in a protrusible penis.In females,there is a single egg pouch,which is also thought to derive from a pair of appendages