Nitrogen Excretion in Aquatic Crustaceans

Abstract

This chapter summarizes the current knowledge of processes involved in nitrogen excretion in aquatic crustaceans with focus on the species-rich (up to 10,000 species) infraorder Brachyura, the true crabs (Martin and Davis 2001). Besides the introduction that briefly covers pathways of the synthesis of nitrogenous waste products and the toxicity of ammonia, organs involved in the excretory processes will be introduced, such as the antennal gland and the gills. More emphasis will be given toward the gills and their capability to actively excrete ammonia in different haline species including the marine crabs Cancer pagurus and Metacarcinus magister, brackish water living Carcinus maenas, as well as freshwater dwelling Eriocheir sinensis. In more detail this chapter reviews the branchial ammonia excretion mechanisms in the green shore crab C. maenas, which is summarized in a working model at the end. Here the potential roles of the Na+/K+-ATPase, K+-channels, Rh-proteins, V-type H+-ATPase, the microtubule network, Na+/H+ exchangers (NHEs), ammonia transporters (AMTs), and aquaporins (AQPs) will be discussed. Besides cited literature, this chapter contains original data as well as cross-references to corresponding chapters within this book.