Salt and Water Balance in the Terrestrial Phase of the Inland Crab Holthuisana (Austrothelphusa) transversa Martens (Parathelphusoidea: Sundathelphusidae)

Abstract

Holthuisana is extremely tolerant of dehydration and withstands loss of ca. 45% total body water. During dehydration, water is lost at an equal rate from both hemolymph and tissue compartments. Dehydrated crabs rehydrate by drinking or by absorption of moisture condensing on permeable surfaces, but they cannot absorb water from damp clay soils. In the field, survival is enabled by construction of a vertical burrow (50-70 cm) in heavy clay soil which retains moisture and, therefore, provides high burrow humidity for long periods. The only sources of water available to the crabs during drought are condensation within the burrow and metabolic water.