Lack of inter-individual information exchange among migrating Cerithidea decollata (Mollusca Potamididae)

The gastropod Cerithidea decollata typically feeds on mud at the mangrove soil surface at low tide and rests on Avicennia marina trunks throughout high tide. Tens of individuals can be observed climbing the trunks and clustering, 2–3 hr before the incoming high tide, approximately 40 cm higher than the level that the tide will reach. As soon as the water disappears, snails descend and disperse on the ground again. Signals able to tell the snails the height of the incoming tide are still unknown but we wanted to investigate whether or not some information may be transferred from resident snails to snails translocated from areas undergoing a different tidal regime. Snails from sites where tides never exceed 5 cm above ground level (translocated) were transported to sites flooded by higher tides (up to 80 cm above the ground), and their behaviour was compared with local snails (residents). At the beginning of the experiment, sea water occasionally made contact with translocated snails as they ascended the trunks later than resident snails and clustered closer to the water. After several tides, translocated snails started to behave similarly to resident snails and, by the 10th tide, the behaviour of the two groups was indistinguishable. However, the behaviour of translocated C. decollate was not affected by being in contact or not with resident snails; thus, it appears that no information was transferred from resident to translocated snails.