How small can malacostracans be?

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hermit crab — malacostracan Hermit crab (*Pagurus samuelis*).

Malacostracans exhibit a vast range of sizes, with some species measuring less than one millimetre (0.04 inch) in length. While many members of the class Malacostraca are medium-sized—typically between one and three centimetres—the adult stages of certain parasitic and subterranean groups are exceptionally small, falling below the one-millimetre threshold.12

This class, which includes crabs, lobsters, and isopods, displays the greatest size diversity within the subphylum Crustacea, extending from these microscopic forms to giants with limb spans exceeding three metres (10 feet).12