Hutchinsoniella

Hutchinsoniella is a genus of small benthic crustaceans placed in the class Cephalocarida. Members of this genus are minute, translucent animals adapted to life in muddy or sandy sediments, where they live interstitially or just beneath the surface of the substrate. Hutchinsoniella species are sometimes referred to informally as cephalocarids or horseshoe shrimps.

Morphologically, Hutchinsoniella species exhibit a simple, elongate body plan with a distinct head and a series of trunk segments bearing homonomous limbs. They lack a carapace and eyes and have relatively unspecialized appendages compared with many other crustaceans. Feeding is accomplished by generating currents with the thoracic limbs and collecting detritus, biofilm and suspended particles; they function as detritivores and microphagous suspension feeders in soft-bottom ecosystems.

The genus is the representative taxon of cephalocarids and includes a small number of described species that occur in coastal and continental shelf sediments in various parts of the world. Reproduction involves direct development, with juveniles resembling miniature adults rather than passing through distinct planktonic larval stages.

Hutchinsoniella and other cephalocarids are of interest to zoologists and evolutionary biologists because their simple morphology and presumed primitive features provide comparative data for reconstructing crustacean and arthropod evolutionary relationships. Field records are relatively uncommon due to their small size and cryptic habitat, so distributional and ecological information remains incomplete.