Velella – The Uncommon Visitor to the San Juan Islands

March 10, 2018

In the past couple of weeks, our guides have noticed an uncommon visitor to the San Juan Islands, Velella or “by-the-wind-sailor”.

These kiwi-sized creatures have been noticed washed up on beaches and caught among kelp beds close to shore. Examined closely, they resemble large translucent thumbprints with an extra fin running crosswise along one side.

Normally, Velella are open ocean dwellers. They are often documented far off-shore drifting in massive groups . Strong winds sometimes blow millions of them onto beaches, as was reported on the coast of Washington, Oregon, and Vancouver Island in 2014. While considered rare, mass standings have been reported in virtually all shoreline areas over various years. This year, the winds were strong enough and directed in such a way as to push these creatures into the Salish Sea. Unlike the beaches of the outer coast, by the time the Velella reach San Juan beaches they are no longer blue-tinted. Most of them has desiccated away, leaving just a translucent whitish structure.

Velella Velella are hydrozoans (cnidarians) found in all the world’s oceans. Each sailor is actually an entire colony of very small hydroids. Although similar in many ways to the Portuguese man-of-war, it is not very closely related. Floating on the surface of the ocean, their small stiff sails propel them according to the winds. A sailor can have either a left or right facing sail. This polymorphism affects the direction in which they ultimately travel. They feed primarily on plankton, using tentacles that drift beneath them in the water. Their blue pigmentation is both sun protection and camouflage. It is also a result of a symbiotic relationship with single-celled organisms that utilize sunlight to provide the Velella with additional energy.


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