'ten-footed') is a large order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, and prawns.

[2] A 2019 molecular clock analysis suggested decapods originated in the Late Ordovician around 455 million years ago, with the Dendrobranchiata (prawns) being the first group to diverge.

High species diversification can be traced to the Jurassic and Cretaceous periods, which coincides with the rise and spread of modern coral reefs, a key habitat for the decapods.

[3] Classification within the order Decapoda depends on the structure of the gills and legs, and the way in which the larvae develop, giving rise to two suborders: Dendrobranchiata and Pleocyemata.

[5] Those groups that usually walk rather than swim (Pleocyemata, excluding Stenopodidea and Caridea) form a clade called Reptantia.