Question sent by JOSEP MONFORT (Castellón). ALBERTO MARTÍNEZ-ORTÍ answers:
The formation of these clusters, sometimes formed with many specimina, also called “grappes”, is a strategy land snails use to fight the high temperatures of the ground and the low levels of humidity in the summer. The snails climb up the stem of leafless plants or trunks so as to avoid dying of dehydration. They hold on to the vegetal substrate creating epiphragm, which can be created in about 10 minutes. During the summer months (up to four), snails remain dormant, reducing their metabolism and heartbeat to half.
Alberto Martínez-Ortí. Malacologist, Valencia.