Dive Dry with Dr. Bill

057: Don't Play With Fire... Worms

Occasionally readers of this column ask me to identify a critter they have found in our waters or on the island. We island residents depend on the Post Office and Vons as places to meet and carry on personal and other business. Therefore it was no surprise when Mary Stein stopped me while walking through the meat section (guess where). She described an unidentified creature that had been turned in to DBOS. I said I'd be happy to take a look at "it." The next night, again in the meat section, Tim Martinelli asked if I'd seen "it" yet. Apparently Tim and his daughter Alessandra discovered "it" on the rocks at Descanso while beachcombing.

Based on the descriptions given, I was uncertain of "its" identity. Mary later brought "it" up to my home to show me. I took a look and realized "it" was something I'd seen in the waters of the Gulf of California (Sea of Cortez), but never here on Catalina. "It" was a form of polychaete worm known as a bristleworm, specifically the ornate fireworm. I checked the published distribution records again, and they stated "throughout the Gulf to Panama, and the entire Caribbean." Even my rudimentary knowledge of geography was enough to realize Catalina was not within those boundaries. Maybe this was a new distribution record for the species!

I contacted diver/biologist Dr. Jack Engle of the Channel Islands Research Program (CIRP). He has probably done more scientific diving around this region than anyone I know. Jack quickly replied that he started seeing ornate fireworms along the leeward coast of Catalina in 1998. He has collected more than 70 specimens at Willow Cove and Empire Landing over the past five years. Lorraine Sadler later mentioned finding one at Pebbly Beach.

I encountered the ornate fireworm around islands in the Gulf of California last winter while working with Lindblad Expeditions. The other naturalists and I immediately warned those who found them under rocks in the intertidal not to touch them. The name "fireworm" comes from the fact that the thin glass-like setae ("hairs") extending from the body can penetrate human skin and inject a toxin that burns like fire. Now that I'm aware fireworms are being found here, I decided to write this column to warn local divers, snorkelers and beachcombers about them.

Fireworms along with earthworms are segmented worms or annelids. This new species belongs to a group of worms known as "bristle worms." Their dorsal surface is covered with orange-red and yellow gills. Many of the setae, or needle-like bristles, extend from each side ready to defend the worm against attack by a potential predator (or curious diver). When they penetrate an attacker, the setae inject a toxin which will not soon be forgotten. When embedded in your skin, the setae are not easy to remove without breaking them. Remaining in the skin, they cause inflammation, itching and irritation combined with numbness from the toxin.

The 1997-1998 and the earlier 1983-1984 El Ninos were among the strongest on record. The extremely warm waters associated with these events allowed some tropical and subtropical species, normally found far to the south, to enter our region. It is believed the ornate fireworm reached Catalina during the later El Nino. Of course it is possible, but less likely that it arrived in the bilge water of a ship that stopped down there and then visited Catalina. Interestingly it is not found along the Baja peninsula's cooler Pacific coast, so this was quite a jump in distribution. According to Dr. Engle, other species introduced during this event include the pink cardinalfish, the Panamic arrow crab and the Pacific wing oyster which joined the finescale triggerfish, scythe butterflyfish and orange throat pikeblenny which reached Catalina from southern Baja earlier.

The ornate fireworm is known to be a hungry predator, feeding on a wide variety of prey. Here it has been seen feeding on Navanax (a relative of the nudibranchs or shell-less snails), tube worms and even bat ray poop (oh, how tasty!). On Catalina it has been observed in habitats with silt or sand substrate in sheltered areas, usually crawling on the surface. In its native region it is often found under rocks in the intertidal, but may live as deep as 300 feet.

Reproduction in bristle worms is interesting. They develop an extra body part which contains their sex cells and is complete with "eyes" and swimming appendages. This part breaks off the worm, rises to the ocean surface and releases the sex cells... nowhere near as much fun as our own species' reproductive rituals. The ornate fireworm probably reached our waters by drifting with the currents while in its planktonic larval stage. It appears to have adapted to Catalina's cooler waters and may be reproducing here, making it something for residents and visitors to be aware of.

DON'T TOUCH these critters with your bare hands. The damage they can cause a human may be severe enough to require amputation of the affected fingers in extreme cases. Diver's gloves MAY offer sufficient protection from the setae and their toxin. Be careful when turning over rocks in the intertidal, and watch your kids if they are doing so (of course always return the rocks to their previous position). So don't play with "me" 'cause you're playing with fire... worms. Of course your chances of finding one are about as good as being struck by lightning, right Tim and Alessandra?

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: Ornate fireworm (approximately 3" long); soft underbelly of worm;
gills on dorsal surface; hair-like setae for self-defense

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia