Description: Like all members of Family Sabellidae (parchment tube worms), this species has a plume of pinnate, featherlike radioles on its head region and lives in a flexible, leather or parchment-like tube it has secreted. Like serpulids (calcareous tubeworms), the head has a series of pinnate radioles with which the animal suspension feeds. Unlike serpulids, the radioles are not spiraled but form a series of semicircles around the head region. In Myxicola infundibulum none of the radioles have conspicuous ocelli curled around them near their tips (The do, however, have ocelli, as demonstrated by their rapid withdrawal into their tube when a shadow passes over them). Unusually, the proximal part of the radioles are connected to one another by a membrane so that they form a funnel (photo). The thorax is longer than in most local sabellids--8 setigers (setae-beaering segments). The first 5 or 6 thoracicneuropodia have long-handled uncini (not avicular uncini) and no pickaxe-shaped setae. The abdominal uncini occur in rows that extend much of the way around the segments and they have several apical teeth. They secrete gelatinous tubes of mucus. The color of the plume of radioles is yellow to greenish, brown, or brownish-purple. Worm is up to 9 cm long.
How to Distinguish from
The membrane which connects the base of the radioles,
forming them into a funnel, is a distinctive feature of this species
combined with abdominaluncini
which form bands nearly around the body. A second, related
asthetica, has also
been reported to be in the region. It has only 1-4 thoracicsetigers
and a single
on the abdominal
and it often attaches to ropes.
Geographical Range: Pacific coast of North America from the Bering Sea to California and in the Atlantic Ocean and Mediterranean Sea.
Depth Range: Intertidal to 425 m.
Habitat: In rock crevices or on floats. Sometimes buried in soft mud.
Biology/Natural History: These worms are often found as an aggregation in which the individual members secrete so much slime that they make a boulder-shaped colony. They withdraw rapidly into the clear mucus tubes when disturbed or when a shadow passes over. Silt and small debris may cover the mucus, masking its transparency (photo). At other times, they build their mucus tubes wedged between other species of worms, mussels, or tunicates.
This species can withdraw into its mucus tube very rapidly, by use of a giant ventral axon. That axon extends throughout the length of the body and has been the subject of much research on neural activity. It comprises 27% of the animal's entire nervous system. Nerve impulses travel at 6-20 m/s along the axon. The quick withdrawal into the tube not only shelters the worm from predators but forcefully ejects wastes from the tube.
Unlike in some other sabellids, the crown of radioles is not autotomized to escape predators, and if the animal loses its radioles it will likely die. Previous authors have claimed that this species cannot regenerate, but this has been disproven more recently, at least in specimens from the Mediterranean Sea (Licciano et al., 2015)
The name 'Myxicola' means 'living in slime' and 'infundibulum'
to the funnel shape formed by the radioles.
Kozloff, 1987, 1996
General Notes and Observations: Locations, abundances, unusual behaviors:
Authors and Editors of
Salish Sea Invertebrates web site provided courtesy of Walla