Shell Water and Its Regulation

Abstract

It is a well-known fact that littoral and semi-terrestrial crustaceans, when staying ashore for a shorter or longer time, often carry some external water, usually retained in the branchial cavities (Wolvekamp & Waterman, 1960; Edney, 1960). The main purpose seems to be to moisten the respiratory surfaces and thus to enable breathing. Species such as Grapsus, Ocypode and Uca, as well as sometimes more aquatic species such as Eriocheir, vigorously aerate the water present in the branchial cavities. In more terrestrial species such as Gecarcinus, Cardisoma and Coenobita branchial water is not an absolute necessity; more or less moist respiratory surfaces seem to be sufficient.