Dive Dry with Dr. Bill

116: Myxicola or Coca Cola?

What do Myxicola and Coca Cola have in common? Absolutely nothing except the cola ending (but not the cola taste). No, Myxicola is not the drink of a new generation. Instead it is a somewhat common segmented worm found in the Dive Park. This worm belongs to a group known as the sabellids. They are also called fan or feather duster worms, and this species is sometimes referred to as the slime feather duster or the jelly tube worm. I commonly see much more beautiful species in more tropical waters. Don't tell our species as I wouldn't want to hurt its feelings! Besides, beauty is in the eye of the beholder.

Upon researching this relatively obscure creature, I was surprised to find its distribution is much broader than I expected. I have seen reports from Russia, Norway, Ireland, England and Nova Scotia. In America it ranges from Maine to New York, and Alaska to southern California. The population in San Francisco Bay is thought to have been introduced from the Mediterranean.

These worms are occasionally found with their thick tubes of jelly-like mucus buried deep in soft sandy or mud sediments. The genus name Myxicola means "slime dweller." Where are Bill Murray and Dan Akroyd when you need them? I most often see them between the "roots" on the holdfasts of kelp in deeper waters. However, I also found them sticking their heads out of tubes in trapped sand on the local rocky reefs. The head is surrounded by a crown of grayish feeding tentacles that overlap for most of their length, forming what appears to be a funnel. The tips of the tentacles are separated giving the funnel a saw blade like perimeter.

Many feather duster worms are found in rocky areas where soft sediments in the water pose less of a problem. In this species the "funnel" is the feeding structure of the worm, and is used to capture plankton. However, because it lives in soft sediments, there is an outer sheath that forms a protective barrier. This prevents clouds of fine sediment from falling on the inner crown which is used to breathe. The fine sediments would clog this apparatus. There is some cost for this protection as it makes the filter feeding less efficient in these worms.

I never see the actual segmented bodies of these worms because they are hidden within the tube. The animals reach lengths of about eight inches. Their bodies are reported to be dark yellow or orange in color. There is a very long nerve chord in the body, one of the longest of any animal. It allows this worm to react quickly to a predator, or a clumsy diver like myself. They immediately pull down into the tube, compressing their body in half lengthwise.

So what makes this strange little worm relevant to humans? There is no commercial fishery for these soft bodied critters (nor should there be!). For one, the unusually long nerve is studied by scientists to see how quickly messages travel along it. Second, I was interested to discover that they are used in toxicity tests to determine the levels of certain chemicals including pesticides that might be permissible in water. The poor little critters are subjected to chlorides of copper, iron, lead, manganese, chromium, mercury, cadmium, silver and zinc as well as aluminum sulfate. I guess if anything has to be subjected to such abuse, better them than me!

© 2004 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.

Images of Myxicola with the crown or funnel extended and two of the animal withdrawing into its tube.

This document maintained by Dr. Bill Bushing.
Material © 2004 Star Thrower Educational Multimedia