SAN FRANCISCO, CA — If you’ve stepped onto Ocean Beach, Baker Beach, or Crissy Field this week, you may have noticed the shoreline looks like it’s been hit by a blue oil slick.
Billions of translucent, cobalt-blue “blobs” are blanketing the sand across the Bay Area and stretching down the California coast. While they look like alien invaders or discarded plastic, these are Velella velella—more commonly known as “by-the-wind sailors.”
The Bay Area Telegraph got to to experience (and photograph!) these weird, ancient little creatures firsthand in SoCal a few years ago. Here’s what to know about them, now that they’re here in the Bay.
What Exactly Are They?
Despite their appearance, they aren’t true jellyfish. They are hydrozoans, a colony of tiny individual organisms working together as one.
Each creature features a stiff, triangular “sail” that sits atop its oval-shaped body. Unlike most sea creatures that swim or follow the current, Velella are entirely at the mercy of the wind.
Why Is This Happening Now?
This mass stranding is an annual spring phenomenon, but experts say the sheer volume this year is striking.
- The Wind Shift: Normally, these sailors stay far offshore. However, strong spring winds and recent storms have pushed them toward the coast.
- The “Lefty” Problem: Interestingly, Velella in the Northern Hemisphere are mostly “left-handed,” meaning their sails are angled to the left of their body. This usually keeps them offshore, but when the prevailing winds shift toward the land, the entire population is steered right onto our beaches.
- The El Niño Factor: Marine biologists at the California Academy of Sciences note that mass strandings are often more frequent during El Niño years when warmer waters bring these tropical-leaning creatures further north.
Are They Dangerous?
For most beachgoers, the answer is no—but there are caveats:
- The Sting: Like their cousin, the Portuguese Man o’ War, Velella have stinging tentacles. However, their venom is generally too weak to penetrate human skin. You might feel a tingle on your fingers, but if you touch your eyes or mouth after handling one, you’ll regret it.
- The Smell: While they look beautiful when fresh, they don’t age well. Within a few days, they dry out, turn white like “cellophane candy wrappers,” and begin to emit a pungent, fishy odor.
- Keep Pups Away: Pet owners should be cautious. Ingesting Velella can cause gastrointestinal distress and mouth irritation for dogs.
The Circle of Life
While the sight of billions of dying creatures might seem tragic, it’s a natural feast for the ecosystem. They are a primary food source for Ocean Sunfish (Mola mola) and purple sea snails.
Delicious!
