Violet sea snails sail on a bubble raft and eat jellyfish

May 7, 2018, 9:32 a.m.
The violet sea snail with a bubble raft
Photo: Scott T Slattery/Shutterstock

These beautiful pale snails look fragile, but they're hardy travelers and fascinating hunters!

The violet sea snail, Janthina janthina, is a pale purple gastropod found all around the world in tropical and subtropical waters. The little traveler spends its entire life adrift on the ocean surface using a raft made of bubbles.

While other snails leave a slimy trail behind them as they travel, this species takes another tack. It excretes mucous from a gland on its foot, and agitates the water around it to create bubbles that it traps inside the mucous. Voila! An inflatable boat.

This is a critical part of life for the snails because they lack the ability to swim. If the bubbles become dislodged from the shell, the snail will sink and die.

Beyond worrying about keeping its bubble-raft intact, life isn’t care-free for the violet sea snail, which is food for a wide range of predators including birds, sea turtles, fish and other mollusks.

Meanwhile, it seeks out other floating organisms as a snack, particularly the hydrozoan species Velella velella (also called by-the-wind-sailors) or the siphonophore species Portuguese man-o-war, Physalia physalis. That makes these snails a friend of humans, as Portuguese man-o-war are infamous for their painful stings.

So, if you ever see a violet sea snail, first marvel at its beauty and ingenuity, and then thank it for keeping those pesky siphonophores in check!