Caribbean beauties in the spotlight

Cuban land snails come in a variety of color variations. © Bernardo Reyes Tur

They shine in a colorful variety, are equipped with “love arrows” – and threatened because of their beauty: The Cuban land snails were chosen by scientists and interested laypeople as the ambassadors of the mollusks for the year 2022. A research project is now also being dedicated to the title holders: the genome of the Cuban land snail is to be sequenced. This could provide insight into the basics of their amazing color variations, among other things.

The first was the whorl snail in 2003, followed by another species of snail, bivalve or cephalopod each year, which was declared mollusc of the year. With the title, the initiators of the campaign want to draw attention to the importance of these creatures, which are often neglected, and to the threat to many species. Since last year, the Senckenberg Society for Natural Research and the International Society for Mollusc Research have ensured a broad basis for the election of the mollusk of the year: First, scientists and laypeople are called upon to nominate mollusks. The board of trustees then selects five types of finalists from the suggestions, which can then be voted on online.

Colorful hermaphrodites

In this way, the Cuban land snails (Polymita picta) emerged as winners from a total of almost 50 nominations this year. These two to three centimeter long relatives of our European “house snails” are found along a narrow stretch of coast in eastern Cuba, where they feed on moss and lichen on tree bark. Like other land snails, Polymita picta is bisexual: the animals are male and female at the same time, but cannot fertilize themselves. They are therefore dependent on a pairing. The “love play” of the Cuban land snail includes a bizarre aspect that is also known from other land snail species: They ram an arrow-shaped calcareous structure into their partners’ feet. It is assumed that sex hormones are transmitted that serve the reproductive success.

Despite its small distribution area, the Cuban land snail was a comparatively prominent species even before the election: Due to its radiantly beautiful shell with light and dark bands, it is considered one of the most beautiful snails in the world. The special thing is that the animals within the species have many different color variations and patterns: the palette ranges from almost white to yellow and orange to reddish and dark brown. However, the beauty is the species’ undoing: although officially forbidden, the snails are collected and their shells are sold to tourists or sent abroad. In addition, the habitat of the Cuban land snail is threatened, so that it is now classified as critically endangered.

Title with sequencing as an award

The species was nominated by Bernardo Reyes-Tur from the Universidad de Oriente in Santiago de Cuba. He was supported by Angus Davison from the University of Nottingham. “We are delighted that this beautiful snail has been named Mollusk of the Year 2022. The prestige will draw attention and give further impetus to conservation efforts,” hopes Davison. “In addition, the prize associated with the choice – full genome sequencing – will allow us to start studying the biology of this snail.” The LOEWE Center for Translational Biodiversity Genomics in Frankfurt am Main will now deal with this task. “We are pleased that with the Cuban land snail, a very interesting mollusc species was selected,” says laboratory manager Carola Greve. “So far there are only a few species of molluscs whose genome has been completely sequenced – even though they form the second largest animal phylum after the arthropods,” emphasizes Greve.

Among other things, genome sequencing could clarify the extent to which Polymita picta is divided into subspecies. “Basic taxonomy is crucial for the conservation of these animals,” says Bernardo-Reyes-Tur. The focus is also on the color variations: “Why are the housings so different? Which genes are involved in color formation?” the researcher wants to find out. There may also be clues that shed light on the strange use of the love arrows. “The genome sequence is a unique opportunity to answer some questions and to promote nature conservation,” Bernardo-Reyes-Tur is convinced.

Source: University of Nottingham, Senckenberg Research Institute and Nature Museums

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