Fig. 8. CE exposure, time to explore and shadow responses. Top, the mean (±s.e.m.) time to explore for snails placed in PW after a 2 h exposure to PW, CE or BC. Time to begin to explore in the CE treatment was significantly longer compared with snails in PW and snails in BC treatment (N=54, ^*P<0.001, one-way ANOVA). Bottom, snails in CE elicited full pneumostome withdrawal significantly more often when presented with a passing shadow than did snails in PW or BC (from Orr et al., 2007).