ABSTRACT
Also called ‘diapause’ and ‘hibernation’ (Hyman, 1967, p 613), aestivation refers to the phenomenon of ‘deep sleep’ undertaken by animals with no access for water and food to overcome unfavorable environmental conditions. The duration of aestivation may be as short as few hours/days, but regularly recurs, as in bivalves inhabiting intertidal zone and as long as from 1 month (e.g. Pila globosa, see Table 5.2) to 2-6 years in freshwater pulmonate Planorbarius corneus (Table 5.1) and as long as 23 years in a terrestrial snail Oxystyla capax (Hyman, 1967, p 613). In this chapter, the former is named as tidal aestivation and the latter as seasonal aestivation. Being an unusual phenomenon but ubiquitously occurring in animals from freshwater sponges to polar bears, aestivation has attracted much attention from the point of subcellular and molecular biological aspects (e.g. Navas et al., 2010). However, the present chapter is limited to physiological and ecological aspects of aestivation in aquatic molluscs from the context of reproduction.
