A graduate student at the University of Gothenburg, Erica Wik, discovered an unfamiliar species while conducting research on eelgrass restoration at the Tjärnö Marine Laboratory in Sweden. The unexpected find occurred just weeks after Wik planted eelgrass seedlings as part of her master’s thesis.
Wik sought assistance from experts at the laboratory to identify the species. “I didn’t recognise it at all, and it wasn’t mentioned in the Encyclopedia of the Swedish Flora and Fauna,” said Helena Samuelsson, an illustrator and former lab worker.
After extensive research, including reviewing scientific literature provided by a marine biologist at Tjärnö, the team identified the creatures as Haminella solitaria, commonly known as bubble snails. According to the university’s announcement, this marks a new arrival for Sweden.
Bubble snails are notable for their transparent shells and distinctive egg masses that resemble clear bubbles. “I have to clear away egg masses all the time,” Wik said. “But it doesn’t matter too much, the snails don’t interfere with the experiment and they eat the filamentous algae, which is good for the eelgrass.”
The species typically inhabits shallow waters with muddy or sandy bottoms and feeds primarily on algae. It can grow up to about 1 centimeter in length—roughly pea-sized—and has tentacles located behind its head.
Marine biologist Kennet Lundin explained that bubble snails have already established populations in Denmark and likely reached Sweden via ocean currents. “This is a species that’s spreading,” Lundin said.
Experts noted that Haminella solitaria was first reported in Europe in 2016 along Germany’s Baltic coast. There is speculation that it may have been introduced from North America through ballast water transported by ships. Bubble snails are common along North America’s east coast.
