decapods

Decapods are an order of crustaceans within the class Malacostraca. The name derives from Greek dekas, ten, and pous, foot, referring to their ten walking legs (pereiopods). They typically have a cephalothorax covered by a carapace and a distinct abdomen. The first pair of thoracic legs often forms claws (chelae), while the remaining four pairs are used for walking. Most species possess stalked eyes and gills located near the thorax.

Decapods are divided into two main suborders within the order: Dendrobranchiata and Pleocyemata. Dendrobranchiata includes penaeoid shrimps, while Pleocyemata includes most crabs, lobsters, crayfish, and other shrimps.

Habitat and life cycles vary. Most decapods are marine and benthic, with freshwater representatives such as crayfish and some shrimps. Reproduction often involves external fertilization and free-swimming larvae, with developmental stages that may include nauplius, zoea, and mysis before reaching the juvenile form; some species brood eggs and give birth to direct-developing young.

Economic and ecological significance. Decapods support major fisheries and aquaculture, providing lobster, crab, shrimp, and prawn meats. They also play key roles in marine and freshwater ecosystems as predators, scavengers, and prey. Conservation concerns include overfishing, habitat degradation, and climate change, which can affect population dynamics and ecosystem balance.