What is the carapace of a malacostracan used for?

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

The carapace in malacostracans is a protective fold that originates from the back of the head. Its primary function is to cover and shield vital body regions, including the thorax, the bases of the legs, and the gill chambers.12

By enclosing these areas, the carapace serves as a protective housing for the animal's respiratory organs and limbs. In many species, it may also project forward to form a rostrum, which is often a pointed, toothed structure. While it is a widespread feature among crustaceans, it is important to note that the carapace is not present in all malacostracans; it is notably absent in groups such as isopods and amphipods.12