My e-mails this summer have worms.

On a barnacle-covered rod in the Gulf of Mexico, a reader saw several dark blue creatures that looked like giant marine caterpillars. They had two rows of white spikes on their backs with “;feelers”; on their tips that could retract. When the reader picked one up with a shovel, it stretched out like a snake. The unsigned note said, “;I'm curious as to what these creatures are.”;

I am, too.

Another unnamed reader recently found a bunch of pink wormy things along the Kailua shoreline. The creatures were about an inch long and curled up like a shrimp with bristles along the inside. “;The bristles didn't seem to come out of the sides like a fireworm, and it didn't have a sting when I touched it,”; the note said. Any ideas?

I don't know what either reader saw but, yes, I do have an idea. Both these animals sound like bristle worms.

This is no brilliant deduction. The world's oceans host 8,000 species of these worms grouped into 86 families. Polychaetes, as this class of animals is also called, come in such a variety of forms and have such diverse lifestyles they're a good guess for any segmented wormy thing you see in the ocean.

Deciding which kind of bristle worm you're seeing is another story. Some, however, such as Hawaii's feather dusters, are easy to identify.

These creatures don't look like worms because their bodies are hidden inside leathery, self-made tubes that extend deep into reef cracks. The part of the worm we see is its delicate fan that comes in orange, purple and brown patterns and looks like, well, a feather duster.

The worm breathes and eats with this 3-inch-wide organ, collecting animal particles from passing currents. If you wave a hand over a feather duster, your shadow will cause the worm to instantly withdraw its fan into its tube.

A similar noticeable polychaete in Hawaii is the Christmas tree worm. When startled, it also retreats into its tube, slamming its door, a tiny shell with spines, behind it. Christmas tree worms build their tube homes in living coral and extend their two fans at the same time. These look like half-inch-tall pine trees except they're bright blue, yellow, orange or tan.

Some researchers think Christmas tree worms help protect coral from the coral-eating crown-of-thorns starfish.

Spaghetti worms, also common on the reef, live in tubes, too. When these creatures extend their sticky white tentacles along the ocean floor, they look like spilled spaghetti. If you touch a spaghetti worm's angel hair feeders, it quickly reels them in.

You don't, however, want to touch another kind of bristle worm common in Hawaii, the well-named fireworm. These pink, orange or green worms nose around the reefs like centipedes. Also like centipedes, they're packing. Fireworm stings aren't medically dangerous, but their toxic bristles can break off in the skin and cause a painful rash.

Polychaete reproduction varies as widely as the animals themselves, from shedding eggs into the sea to casting off body parts in swarms of reproductive frenzy. Some eggs become well-developed larvae before they turn into young worms.

I don't want worms in my computer and have programs keep them out. As e-mail subjects, however, all worms are welcome.