When the animals were induced to estivate (Table 1), they first crawled on the dry surface, and later became immobile. Seventy two percent of them had already retracted into the shell by 10 h after being left on the dry surface; however, the latter were all keeping a slit between the shell aperture and the operculum. 24 h after induction, however, half of the animals had the elastic operculum tightly adhered to the shell, while the others were either still attached and immobile (22%) or already retracted into the shell (28%). All animals had the operculum tightly closed at 48 h after the beginning of observations.
The arousal response was induced by water exposure (Table 2). Detachment of the operculum was first seen in 28% of animals 5 min after induction (Fig. 2B). Extrusion of an exploring tentacle was occurring in 72% of animals 20 min after induction (Fig. 2C), and the head and foot was starting to deploy and both tentacles were being turned outward in 56% of animals after 30 min (Fig. 2D), while 11% of animals were either still attached to the vessel wall or were already crawling (Fig. 2E). At 5 h, 17% of animals had already eaten lettuce, and 83% of them at 10 h (Fig. 2F).