Hundreds of thousands of Velella velella on Zmudowski State Beach
in Monterey Bay.

Millions of By-the-wind Sailors, or Velella velella, have been washing up on Sanctuary beaches this past week. These small Hydrozoans normally float at the surface in offshore waters, but the recent southerly and westerly winds have brought them on to the beach. Because of their iridescent coloring, even to the trained eye they can appear as an oil slick when massed in large numbers on the surface of the water. Their "sail" is a triangular crest set diagonally across the top of the flat, oval base. They can "tack' in the manner of a sailboat. The bright blue By-the-wind Sailors do have stinging cells, but they are harmless to humans. They can grow to be 4 inches long, 3 inches wide, and 2 inches tall.

Velella velella up close and personal on Zmudowski State Beach.

On the surface, Velella velella can appear as an oil slick with their iridescent coloring.

 

Velella velella sailing on the surface.