快猫短视频

Beach life can be tough for creatures that endure ocean tides every day. One species of marine snail, however, appears to have found a clever way of coping with the dramatic changes in conditions 鈥� they wear heatproof coats.

A type of turban snail, so-called because of the shape of their shells, is often found on rocky shorelines around Japan covered in a mat of green algae. While most turban snails will eagerly feast upon algae, Lunella coreensis accumulates it as a vegetative jacket as they grow, until they are entirely covered in it at maturity.

The algae itself also appears to only grow on the shells of this snail, although the reason why was a mystery. Now a study suggests the algae insulates the snails from sudden shifts in temperature as the tide recedes.

鈥淭he snails are regularly out of water and are exposed to sun at low tide,鈥� says Osamu Kagawa, a marine biology student at Tohoku University and lead author of the study. 鈥淭he difference in temperature between low tide and high tide is sometimes more than 20掳C.鈥�

Kagawa and his colleague Satoshi Chiba noticed snails on boulders close to sandy areas of beach often lacked algal coats while those inhabiting rockier areas almost entirely did. When the pair collected the coatless snails, they were far less hardy than those blessed with a covering of algae.

Snails left under heat lamps in the laboratory for 30 minutes 鈥� an attempt to mimic the heat of the sun on the beach after the tide has gone out 鈥� suffered nearly double the mortality rate if they lacked algae compared to those with it.

However, not everyone is convinced by the pair鈥檚 explanation. 鈥淭he rocky-shore probably supports tidal pools that encourages algal growth,鈥� says David Marshall, at the University of Brunei Darussalam. Snails living on the sandy beach can probably also find shade beneath the boulders there, helping them stay cooler. 鈥淭hus there is no advantage of supporting algal growth on the shell,鈥� he says.