A feminine violet snail, Janthina exigua, hangs from a float of home-based mucus.
Scientists have extended observed snails "surfing" the load on such rafts, which can dish up as flotation devices, egg-storage areas, and platform for youthful snails.
But it was unknown how the family of fewer than ten bubble-rafting species evolved their odd lifestyles, said Celia Churchill, a Ph.D. student at the University of Michigan in Ann Arbor.
Churchill had already supposed that bubble rafters evolve from bottom-dwelling snails that create mucus-filled egg masses. To pinpoint the rafting snails' neighboring relatives, the team sequenced DNA from bubble-rafting class and other possible "sister families," using molecular technique to piece jointly an ancestral family tree.
The results exposed that bubble rafters descend from a bottom-dwelling snail call the wentletrap, which still exists today.
Both snail groups exude mucus from their feet-muscular organs at the basis of their bodies. But in its place of making egg masses, the bubble rafters use the quick-hardening mucus to make rafts with the "consistency of bubble wrap,", whose new study appeared recently in the journal Current Biology.