Ocean Watch

Monday, April 13, 1998

Blustery trades deliver
treats to beachcombers

THE tradewinds have been blowing furiously through the islands lately. This means rough times for anglers fishing offshore and boaters trying to cross Hawaii's boisterous channels.

On the other hand, the strong trades bring welcome rain to our drought-stricken islands and make Hawaii's windsurfers happy. At Kailua Beach, they've been hurtling across the water like swarms of delirious butterflies.

Prolonged, onshore winds are also heaven for Hawaii's beachcombers since the islands' stormy weather is so user friendly. I love walking the beach with waves pounding and wind whistling -- and I'm perfectly warm.

When I'm out there enjoying the beach in such blustery weather, I also have a mission: I'm looking for offshore animals the strong winds have blown ashore.

Some of these creatures are small, so I have to look carefully and be alert to the color blue. As an adaptation to living in the open ocean, most wind-drift creatures are blue or purple.

Here's what I found at Kailua Beach:

Portuguese man-of-war. These notorious stingers with the trailing tentacles were named by 18th century English sailors after the once-powerful Portuguese navy.

Although it seems that these floating creatures just drift aimlessly, they can actually set a course. On top of the animal's blue bubble, or float, lies a pink crest, the animal's sail. When there is little or no wind, the man-of-war flattens the crest and drifts with the current.

But when the wind blows, this creature sets sail by raising the crest. In this way, the little "boat" can sail at an angle to the wind.

When the wind blows hard onshore, however, it overpowers the system and pushes the floating man-of-war to their deaths on beaches.

By-the-wind-sailors and blue buttons. These buttonlike, blue disks with tiny tentacles protruding from the edges are also relatives of jellyfish.

Blue buttons, about an inch across, are perfectly flat but by-the-wind-sailors have tiny sails that help them stay offshore. The Latin name for by-the-wind-sailors, Velella, means little sail. They grow to about 3 inches across.

Floating on the water's surface with the winds and currents, both by-the-wind-sailors and blue buttons eat whatever animal plankton has the bad luck to run into them. The small stinging tentacles don't hurt human hands but pack a punch to tiny shrimplike creatures.

Violet snails. These lovely lavender snails, about the about the size of a thumbnail, float upside-down on the ocean's surface, their foot attached to self-made bubble rafts. The bubbles consist of air trapped inside clear, dried mucus.

Violet snails' shells are thin, often breaking like eggshells with the slightest pressure.

What are such delicate snails doing out there on the open ocean? They're eating Portuguese man-of-war, by-the-wind-sailors and blue buttons.

When a violet snail runs into one of these jellyfish relatives at sea, there's no battle. Stinging cells on the jellies' tentacles aren't effective against this shelled predator. When the snails are lucky enough to come into contact with one of their prey, they just start nibbling.

Glaucus. This is a hard one to find. On the beach, it rolls itself up, looking like a blue-and-white pencil eraser. When dropped into a jar of seawater, however, it unfolds like an exquisite flower.

Glaucus is a gorgeous purple-and-white sea slug (nudibranch) that, like the violet snail, floats on the surface eating the above jellies. The slug stores its prey's stinging cells inside its body to use in its own defense.

Next time it's windy, tie down your hat, hit the beach, and think blue. It's a fun way to see some elusive and interesting marine animals.