brachyuran

Brachyuran refers to a large group of decapod crustaceans commonly known as true crabs. The name comes from Greek brachys meaning “short” and oura meaning “tail,” a reference to their relatively brief abdomen that is typically folded under the cephalothorax. The term is used in scientific contexts to describe this clade and its distinctive body plan.

In taxonomic terms, brachyurans are part of the infraorder Brachyura within the order Decapoda. They comprise a broad array of families and include many familiar crab species found in a wide range of habitats. Members occupy marine, brackish, and, in some lineages, freshwater environments, with distributions spanning tropical to temperate regions. A common morphological theme is a broad, shield-like carapace and a small abdomen that is largely hidden under the body.

Morphologically, brachyurans typically have five pairs of walking legs, with the first pair often modified into claws in many species. The abdomen is generally reduced compared with other decapods. Gills are enclosed in branchial chambers, and eyes are usually located on stalks. While most brachyurans are benthic, some groups have adapted swimming abilities, often through modified hind legs.

Ecology and significance: Brachyurans play important roles as scavengers and predators in shared coastal ecosystems and occupy a variety of substrates, from mud and sand to rocky shores and coral reefs. Several species are commercially important, such as the blue crab, Dungeness crab, and stone crabs, contributing to fisheries and human cuisine. The group is also a focus of ecological and evolutionary studies due to its diversity and wide ecological reach.