Violet Sea Snails – A Rare Visitor

For the summer peak season, we’re based out on the Isle of Coll in the Scottish Inner Hebrides islands. The islands are exposed to the North East Atlantic and although the ocean can be a tumultuous place, it also means we have special wildlife and occasional rare visitors.
This summer there was an influx of a very rare visitor and one that I had never seen before. As a marine biologist, I do love smaller critters as much as the big stuff, although most folk wouldn’t get particularly excited about a sea snail – this one is very unique!

The violet sea snail (Janthina janthina) is what is known as a pelagic animal, meaning that it lives its life in the open ocean. Unlike other ‘snails’ the adult of this species lives at the surface of the open ocean only. Rather than crawl around the bottom, they create a ‘bubble raft’ from a type of mucus that traps air bubbles. This keeps it afloat and drifts with the currents. How bizarre!

It uses tentacles to hunt and is known to prey upon another favourite critter of mine, the by-the-wind sailor (Velella velella). This little colonial Hydrozoan rafts float along with a thin sail to help catch the wind and travel. They have electric blue tentacles underneath and an obscure but stunning wee thing. They do seem rather large compared to the snails so we can only wonder how the hunting takes place!

The snails have a neck & head which are mostly missing from the stranded shells if you are lucky will you see the bubble raft. This summer I only found the shells without bubbles, but another naturalist based on the neighboring Isle of Barra did find one, it’s an odd thing to be jealous of – Snail bubble spit! Violet sea snails are found through most sub-tropical and tropical oceans however a very rare occurrence to be found in NW Scotland. It’s always worth keeping a keen eye on exposed Atlantic beaches as you never know what might turn up! We do have a few other finds from this summer which we’ll share in due course!