Their shells come in a wide variety of colours: pastel yellow and pink, brick red and black, pearly white and ochre. Regardless of hue, the markings of the six species of Cuban painted snails, as they’re known, accentuate the whorled shape of their grape-size shells, which swirl in upon themselves. You can get lost gazing at these marvels of nature.
Cuba is home to the world’s greatest diversity of snails having a range of colours and complex patterns. Painted snails, in the genus Polymita, have long been sought by collectors. This demand is one reason why Cuba lists all six species as critically endangered The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has banned their trade since 2017.
It’s not only illegal collecting but also land clearing, predation by invasive species, and climate change has jeopardised their future.
The painted snails inhabit a thin belt of vegetation along Cuba’s eastern coastline. Though scientists don’t know how many painted snails there are, they’ve learned that they occupy small areas because they depend on micro habitats with just the right makeup of plants. Polymita sulphurosa, for example, one of the most vividly coloured of the six, is seen only in a few square miles near wildlife-rich Alejandro de Humboldt National Park.
For the most part, the snails live in trees and shrubs, eating lichens and mosses, sources of the minerals that give their shells the stunning colours. Whether or not the colourations protect them from predators or provide some other advantage remains unknown. The snails are ecologically important as a source of food for native and rare species such as the critically endangered Cuban kite. And By devouring mosses and bark fungi, they also help keep trees healthy, including in coffee plantations.
One species, Polymita venusta, is so sedentary that it stay in the same spot for six months. The snails’ slow-moving ways and picky habitat needs make them vulnerable to disruption. Clearing of land by coffee growers and for other types of agriculture has greatly reduced their ranges. They’re also preyed on by native species such as sparrow hawks, as well as invasive animals, including rats.
Warmer temperatures and more intense droughts associated with climate change pose another threat, potentially making conditions inhospitable for the vegetation the snails need to survive. Climate change alone could virtually eliminate habitat essential for two of the species by 2050.
The Cuban public is becoming more aware of the harm caused by shell collecting and the other threats.