“…Research on Gastropods' defence reactions is almost entirely devoted to interactions in the snail-trematode system (Lie et al, 1981;Bayne and Yoshino, 1989;Loker et al, 1989;Fryer and Bayne 1990;Amen et al, 1991;Yoshino and Vasta, 1996;Adema and Loker, 1997;Horak and Van der Knaap, 1997;Sapp and Loker, 2000; see review : Loker, 2010), but the concentration of researchers on the cellular and humoral processes in snails means that relatively little is known of the ability of snails to generate nonspecific reactions, analogous to fever, which may follow a similar course in all animals. Independent of the systematic position, many ectotherms developed a behavioural mechanism for changing body temperature, involving moving to warmer or cooler microhabitats (Portner 2002;Zippay et al, 2004).…”