Scientists discover tiniest-ever land snail

Needles in haystacks? Child’s play. For a real challenge, try finding a snail in a needle stack.

After combing through soil samples from Southern China’s Guangxi Province, a team of scientists has described seven new terrestrial “microsnail” species. One, dubbed Angustopila dominikae, could be the smallest in the world – at a mere 0.86 mm tall, it could fit in the eye of a needle 10 times over. Researchers described their findings Tuesday in the journal ZooKeys.

The exceptional tininess of these shells presented a challenge for researchers. Covered in mud, each one required precise cleaning before it could be properly identified.

“I knew that it was a new species, and [there was] a single shell,” lead author Barna Páll-Gergely says. “So if I damaged it by accident, I could not describe and name it. Fortunately, I could clean it very gently under the microscope.”

Mr. Páll-Gergely, and his colleagues did not find any living snails – only their calcified homes. And with only empty shells to go on, scientists know little about how these mollusks actually live. But by using related species as a model, researchers can infer that they live at the base of large limestones, and very likely dig themselves into soil or rocky crevices during dry periods.

“These places help them to minimize water loss,” Páll-Gergely says, “which is always a very big problem for land snails. They most probably feed on decaying plants and fungi. We don't know how they find the mating partners, which would be a very interesting research topic.”

While bird and mammal species are extensively catalogued, the same cannot be said for small-scale invertebrates. Páll-Gergely suggests that “thousands” of new tropical species await description.

“In the last five years, I described approximately 50 new species,” Páll-Gergely, a biology graduate student at Shinshu University, says. “And this is not because I am particularly productive or hardworking, but simply [because] there are many new species in the tropics, and interestingly, in museum collections. Every year, about 16,000 new species of animals are described by taxonomist from all over the world. Over 95 percent of these are tiny invertebrates.”

And despite major scientific advances, many – Páll-Gergely included – argue that the fields of evolutionary biology, systematics, and taxonomy are “far behind other scientific disciplines.” While about 1.5 million species have been named and categorized, researchers estimate that some 10 million more have yet to be discovered.

“Although these snails are very tiny, they must be found, examined, and categorized – just as all other larger organisms – in order to know what other creatures share this planet with us,” he says. “Moreover, we do not yet understand their importance in ecosystems; it might be more important than we would imagine from their size.”

“Besides curiosity, detailed knowledge on the Earth's biodiversity helps us to identify biodiversity hotspots and protect our species more effectively,” he adds. “Knowing, naming, and categorizing all organisms is the base of all studies in life sciences.”

But as is often the case with scientific discovery, A. dominikae might create more questions than it answers.

“Our findings provide a basis to ask further questions,” Páll-Gergely says. “How small a snail can get? Why is it so small, and what are the merits and demerits of this lifestyle? This could help us understanding the evolutionary mechanisms of dwarfism in invertebrate animals.”