Snails hatch when it rains because they need very high humidity to survive. The shell protects them from predators and helps them retain moisture in their bodies. These animals flee extreme temperatures. In very dry weather, they bury themselves, even up to two meters deep, or hide under stones or leaves, in sheltered areas near rivers or puddles, always in places where they feel protected from the lack of water. The same behavior is performed in winter.
Snails move on a muscular structure called a foot, which is full of slime glands that secrete what we know as slime. This slime allows them to move. The less dry the ground they move through, the easier it is for them to move. With low humidity, the mucous membrane dries out and at some point they are unable to move, which can lead to death. This drought that we are experiencing in Spain, for example, is affecting them very much. In fact, land snails are among the most affected animals.
When it rains, they can move about more easily, allowing them to reach the places where they find food and perform other physiological functions such as mating and reproduction. In addition, snails are oviparous and usually bury their eggs, so they need a moist and soft substrate.
However, snails do not actually hatch when it rains, but only later, since raindrops can injure them by hitting their body and shell. They also do not come out when there is too much water, as they cannot move easily in wet terrain and may drown. An optimal situation for them is when the environment has a relative humidity between 80 and 90%. His favorite times of day to be outside are dawn and dusk as there is less sun exposure at these times of the day.
When the environmental conditions are unfavorable, snails seek refuge in their shell and close the opening with the epiphragm, a hardened layer of mucus. This helps them maintain humidity and protect themselves from invading predators. In this state, they can resist for a long time and during this time they do not need to eat because their metabolism is very slow and they do not use energy. Nudibranchs, which have a very small shell or no shell at all, burrow, take refuge in crevices in wood or rocks, or seek shelter near bodies of water.
Lola Bragado Alvarez She is a biologist and curator of the Mollusk Collection at the National Museum of Natural Sciences (CSIC).
Question asked by Ruth Lazkoz.
Coordination and writing: Victoria Bull
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