Mass death is the usual reason that by-the-wind sailors (Velella velella) come to our attention. Millions periodically wash up on West Coast beaches and, unable to return to the sea, die.
The ocean-going animal has a translucent blue disc-shape that floats with a triangular sail that catches the wind.
It’s the sail that gives the animal its scientific name (from the Latin velum, a sail). It’s also the part that I find most fascinating. Ocean winds are strong and velella are comparatively fragile. Why doesn’t the sail crack or fall over?
If you look at one closely from above, you’ll see that the sail has a slight S-shape to it that allows it to bend and not break because the shape changes the dynamics of the wind.
That doesn’t mean velella aren’t tossed about during Pacific Ocean storms. But the body is water repellent on its upper surface, so when strong ocean winds tip it over, its design allows it to roll sail-up.
By-the-wind sailors are not totally at the mercy of the ocean winds because of the alignment of the sail on the float. The sail is in the middle but angled about 45 degrees left or right of the long axis.
The sails on West Coast velellas are set to the right; prevailing winds will generally keep them offshore. Sails on velella on the other side of the North Pacific are angled to the left of the main axis; prevailing winds will usually keep that population offshore.
In late winter or early spring, particularly strong winds can blow millions of by-the-wind sailors on our beaches, where they will dry out and die.
Velella are a cnidarian, an animal that lives on the surface of the water, about half above and half below, and has specialized cells used for capturing prey. A by-the-wind-sailor is in the same broad category as anemones, corals and jellyfish.
New research is leading marine biologists to think differently about velella’s classification. They now think of one velella as a colony of separate polyps, small colonial, primitive lifeforms.
A velella is in the polyp phase of the life cycle.
It has a central downward-facing mouth surrounded by feeding tentacles and reproductive stalks. Most velella live less than a year so they grow and reproduce quickly in one of the more interesting creation tales.
Each velella is a colony of all-female or all-male polyps. They bud off thousands of tiny offspring — miniature jellyfish-like medusa — that sink 2,000 feet or more into the ocean, withstanding pressure that would kill us. After fertilization, free-swimming larvae develop a float, pump in gas, and rise slowly to gradually adjust to the water pressure.
Velella velella is a carnivore. This predator uses its short, hollow tentacles with stinging cells to snare zooplankton, tiny crustaceans and invertebrate eggs.
In turn, they become prey of the ocean-going sea slugs, the sunfish Mola mola, nudibrances, violet snails, and bubble-rafting snails, albeit by chance encounters.
After all, it is a big ocean.
Marmot watching: Olympic National Park needs volunteers to survey marmots to determine population and distribution. The iconic Marmota olympus is found only in the alpine meadows of the park and Olympic National Forest.
More than 90 volunteers, working in groups, must be capable of hiking and camping in remote areas, participate each year after a one-day training session.
The deadline is May 1. For information, go to www.nps.gov.
Columnist Sharon Wootton may be reached at 360-468-3964 or www.songandword.com.
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