Ocean Watch

Monday, November 9, 1998

Hunt for worms
entertains with color,
speed, mystery

WHEN I was a kid, I loved to play with worms. On rainy days I waited impatiently for night to fall; then I would creep through the back yard hunting for night crawlers. The brown worms were stretched out in the flower beds, all wet and glistening, then WHOMP, I would snatch them up and drop them into a coffee can full of soil.

The next day, I examined my worms for a while, then gave the can to my grandpa, who graciously accepted it for fishing.

I still like to play with worms, only now my back yard is the ocean and the worms are marine.

Last week, near my boat in the Ala Wai Boat Harbor, I noticed a row of tube worms called feather dusters. These build permanent tube homes in the cracks and crevices of rocks and reef. The tubes, made of mucus, sand and bits of shell, are good protection from hungry fish and probing crabs.

But the encased worm must eat. To do so, it extends a feathery bouquet of tentacles in the shape of one or two spiral funnels.

Tiny beating hairs on the tentacles cause water to flow through the "feathers," where particles of drifting plants, animals and debris get trapped. The beating hairs drive this stuff into grooves on the tentacles and down to the base. There, the worm sorts its catch, rejecting pieces too large to eat, saving pieces suitable for tube building, and eating the rest.

Besides gathering food and construction material, these worms' tentacles also absorb oxygen.

This water-sifting system works well, but such colorful plumage sticking out in front of every passing predator makes the worm vulnerable. And that's where the fun comes in.

Feather dusters have what is called a shadow reflex. That means when an object passes over, the worm withdraws its tentacles in a fraction of a second. Therefore, if you wave your hand near a feather duster, or even pass it over the worm, it will instantly haul in its tentacles.

It's fun to watch a row of feather dusters duck inside their tubes; it's also fun to wait a minute and watch them peek out again. When left alone, the whole row was out again in just a few minutes.

No one knows exactly how this shadow reflex works. Most feather dusters have eyes, which look like dark spots on the main axis of their feathery tentacles. But when researchers remove these eyes, the worms still retreat rapidly from shadows.

Feather dusters are beautiful - sometimes too beautiful for their own good. Once I saw two men chipping at harbor rocks to get worms to sell to aquarium keepers. When I asked them to stop, they ignored me. Soon the area was sadly bare of the lovely creatures.

But now they're back. I still play with them, but I spook the creatures only once, then leave them to eat and breathe in peace.

I feel bad now about plucking those night crawlers. But come to think of it, I don't remember my grandfather going fishing very often. He may have returned the worms to the garden where, like the feather dusters, they continued their job of maintaining a healthy environment.