Beachcombing Report: Purple Sea Snails

Strong onshore winds this week brought in one of the Gulf’s more unusual drifters, the Purple Sea Snail. While riding my e-bike on the beach I found around a dozen washed ashore, many of them still alive. Curious to watch them up close, I placed several in a clear glass of saltwater where they immediately went to work rebuilding the delicate bubble rafts that keep them afloat in the open ocean.

Unlike most snails that crawl along the seafloor, purple sea snails live their entire lives drifting at the ocean’s surface. I found two species this week that include the globe and common sea snails. Both species hang upside down beneath a raft of bubbles they create using mucus and trapped air, forming a floating life raft that allows them to ride the currents across entire ocean basins.

While observing them, a couple of the snails released a splash of purple dye that stained my hand for nearly a full day. This defensive ink contains pigments similar to the famous “Tyrian purple,” a dye once prized by the Romans for coloring royal garments. In ancient times, related sea snails were harvested in huge numbers to produce the valuable purple pigment associated with wealth and power.

Purple sea snails are part of a floating community of ocean drifters that occasionally wash ashore together. I most often find them alongside Portuguese man o’ war, by-the-wind sailors, and blue buttons, organisms that also live at the surface. For the snails, these creatures are not just neighbors but dinner. Purple sea snails are specialized predators that feed on these gelatinous drifters, even consuming venomous Portuguese man o’ war.

One especially neat discovery this week was a small bubble raft floating alone with clusters of tiny purple sea snail eggs attached. Female snails attach their eggs to these bubble rafts, allowing the next generation to begin life drifting on the ocean’s surface.

Jace Tunnell is the Director of Community Engagement for the Harte Research Institute at Texas A&M University-Corpus Christi. His Beachcombing series appears on YouTube (@HarteResearch), Facebook (facebook.com/harteresearch), and Instagram (@harteresearch).