Definition of Malacostraca in US English:


plural noun

  • A large class of crustaceans which includes crabs, shrimps, lobsters, isopods, and amphipods. They have compound eyes, which are typically on stalks.

    • ‘Both volumes begin with a general introduction to the Malacostraca, followed by a historical overview of the most important contributions to Australian carcinology over the past 200 years.’
    • ‘Maxillopoda and Malacostraca are by far the most diverse of the groups and contain most animals you might typically recognize as crustaceans.’
    • ‘Development ranges from direct to metamorphic among members of class Malacostraca.’
    • ‘The other two types of larvae, Zoea and Megalopae, are only found in members of Malacostraca.’
    • ‘On the whole the maxillopodan groups Ostracoda and Cirripedia and the Malacostraca have left the most significant fossil records.’


Modern Latin (plural), from malaco- ‘soft’ + Greek ostrakon ‘shell’.