Andros Island, Sept. 10 — Gordon Hendler is excited. He fetches me from the dinner table in Forfar Field Station's cafeteria, pulling me, as he has all week, into the lab to see another special animal he's found.

After hours upon hours of floating in waters shallow and deep these weeks, his nose inches from the sand, Gordon finally has hit pay dirt: "I'm almost certain this is a new species of brittle star," he says as we watch an elegant creature edge nervously around a petri dish.

Gordon is curator of echinoderms with the Natural History Museum of Los Angeles County. A brittle star specialist, he's found plenty on this trip to be excited about. Living under dead elkhorn coral, on and in sponges, and under the sand, Bahamian brittle stars have five arms that spread from less than an inch across to three feet.

This potentially new species of brittle star dwells beneath the sand, making it almost impossible to find. It's hard to believe that something as delicate as this, with its graceful, undulating arms as thin as thread strands, can survive intact in such a harsh environment.

"I changed fields from mollusks to brittle stars because so little was known about them," says Gordon, who started studying brittle stars 25 years ago.

He's still enthralled with the beautiful creatures, whose arms can be as fine as hair or as thick as fettuccini, and whose colors wander from one end of the spectrum to the other.

The first record of echinoderms appears in the writings of Aristotle. Fossils of the creatures date from the early Cambrian period, nearly 600 million years ago, when there was a concentrated explosion of life on the planet.

There are six classes of the spiny-skinned animals: brittle stars, sea urchins, sea cucumbers, feather stars, sea daisies and sea stars (also known as starfish). Sand dollars and basket stars also are considered to be echinoderms.

Gordon explains how sea cucumbers extend tentacles with small, sticky pads at the ends to capture food swimming by. I'm impressed most by sea cucumbers' ability to shoot out their guts as waste if put under stress. Then they crawl off and hide somewhere while they grow new insides.

"I've had a few sea cucumbers that eviscerated themselves in the collecting bucket," Gordon says.

Since we've been here, Gordon has set in my hand sea urchins with red flesh, or purple-tipped, white-ringed spines that wave around, tickling my palm. I've seen purple or orange starfish that range in size from three inches to more than a foot across. And this potentially new species of brittle star has arms stretching out three inches from a crimson central disk not a quarter of an inch across.

On the boat the other day, I held a sea cucumber nicknamed Donkey Dung that looks just like its name. When I turned it over and tickled its pink, spotted belly, it shot out water from both ends.

But the stars of the show are the brittle stars of sage green, burnt orange, lavender and white, or tan.

Scientists group together these apparently different creatures because of their five-part body plan. Brittle stars and sea stars have five arms, and five petals adorn sand dollars. Even sea cucumbers, which can look like inanimate logs on the sand, have an internal five-part symmetry.

All echinoderms have a skeleton. They also have tiny, fluid-filled tube feet that they use to move, feed, burrow, breathe or perform other tasks.

"Some brittle stars can do the breast stroke along the bottom, and even swim to get around," Gordon says.

And echinoderms can grow new body parts: A sea cucumber can regenerate its innards; a brittle star, sea star or feather star can replace an arm, sometimes in weeks.

Echinoderms can have a big impact on a reef if their numbers are big enough. For example, herds of sea urchins can mow down stands of seaweed and seagrass and excavate deep holes into the rocky framework of the reef itself.

Gordon is content with the amount and variety of echinoderms he's found on the Andros reef, even though he's had to search high and low to find them. On other Caribbean reefs, common species of brittle stars coat sponges inside and out, and swarm in coral rubble. Sea urchins poke out of nooks and crannies of corals in the back reef; troops of feather stars stand sentinel over the deeper fore reef.

Here, though, the common brittle stars that mob reefs from the Carolinas to Brazil, as well as other echinoderms that are abundant elsewhere, seem to be absent.

"Per unit of dive time I've spent here, I'm not seeing nearly as many animals as I've seen elsewhere," Gordon says. "I don't know why, but I have some ideas I'd like to test."

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