See text Harpacticoida is an order of copepods, in the subphylum Crustacea.

This order comprises 463 genera and about 3,000 species; its members are benthic copepods found throughout the world in the marine environment (most families) and in fresh water (essentially the Ameiridae, Parastenocarididae and the Canthocamptidae).

Harpacticoida represents the second-largest meiofaunal group in marine sediments, after nematodes.

Harpacticoids are distinguished from other copepods by the presence of only a very short pair of first antennae.

They typically have a wide abdomen, and often have a somewhat worm-like body.