One of the things a lightkeeper notices on the shoreline are the different changes, be they strange fishing floats, bloated dead fish, defeathered seabirds, massed clumps of seaweed or the profligate carcasses of the By-the-wind-sailor.
I had seen many beaches littered with the pale blue bodies of the By-the-wind-sailor and thinking they were the nefarious Portuguese Man o’ War I hesitated to examine them, fearful of the imagined sting I would receive. It was not until I read the article yesterday on the By-the-wind-sailor from the Monterey Bay Aquarium that I realized that I was in error in my knowledge.
The photo above (click for larger image) shows what I usually found on the beaches. As these free-floating hydrozoans named Velella velella got caught in an adverse wind, they ended up dying on the shoreline by the thousands.
They are actually, when floating on the water, a very beautiful sight. Described by the Monterey Aquarium site:
A type of jelly, the by-the-wind sailor sports a deep-blue, rectangular float topped with an upright, triangular sail. By-the-wind sailors often drift across the ocean’s surface in large numbers, sometimes in the tens of thousands. In late spring or early summer, they’re often blown ashore, blanketing coastal beaches.
So there you have it – what I thought was the dangerous Portuguese Man o’ War was an innocent jellyfish! But it was always better to be safe than sorry – especially in an isolated environment like the lighthouse.
These by-the-wind sailors are also known as sea raft, purple sail, and little sail no means of locomotion other than the sail.