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Phragmatopoma californica (Fewkes 1889)

Brief Summary

    Phragmatopoma californica: Brief Summary
    provided by wikipedia

    Phragmatopoma californica, commonly known as the sandcastle worm, the honeycomb worm or the honeycomb tube worm, is a reef-forming marine polychaete worm belonging to the family Sabellarididae. It is dark brown in color with a crown of lavender tentacles and has a length of up to about 7.5 centimeters (3.0 in). The worm inhabits the Californian coast, from Sonoma County to northern Baja California.

    Sandcastle worms live in colonies, building tube reefs somewhat similar to sandcastles (hence the name), which are often seen on rocky beaches at medium and low tide. The sandcastles, which have a honeycomb-like outward appearance, can cover an area of up to 2 meters (6.6 ft) on a side. They may share areas with mussel beds and are found in any place that provides some shelter, such as rock faces, overhanging ledges and concave shorelines.

    The worms remain in their tubes and are almost never seen. At low tide, when above the water, they close the entrance to their tubes with a shield-like operculum made of dark setae. When submerged, they extend their tentacles out of the tube to catch food particles and sand grains. The grains are sorted, with the best ones used to keep the tube in repair, and the rest ejected. The colonies are formed by the gregarious settlement of larvae, which require contact with an existing colony to metamorphose into adult worms. Gregarious settlement of this species has been linked to specific free fatty acids associated with the tubes of adult worms. On rocky beaches, settlement is dependent on larval behavior in the water column and perception of chemical cues when the larvae contact the tubes.

    Sandcastle worms should not be confused with the similar, but more northern Sabellaria cementarium which are found from Alaska to southern California and have an amber-colored operculum. Unlike P. californica, S. cementarium rarely forms colonies, does not settle gregariously, and its larvae do not respond to free fatty acids.

Comprehensive Description

Behavior

    Tube Dwelling Behavior in the Marine Annelid Phragmatopoma californica (Fewkes)
    provided by EOL authors

    Morphology: Worms are about 2-3cm long. The body is the worm is made up of four sections: head, thorax, abdomen, cauda. The head and thorax are usually in the flared end of the tube when the worm is undisturbed.

    Tube Building Behavior: Sand particles are passed from the tentacles at the head, to the mouth and then to the building organ. In the building organ the grains are coated with the “cement” that the worm uses to build its tube. The coated sand grain is then put into place at the flared end of the tube.

    Tube Dwelling Behavior: When feeding and undisturbed, the worm will extend its head and tentacles out of the tube. If is is threatened, it will contract its body and retract it into the tube. Even when the worm is retracted into the tube, it can increase water flow to the head by thoracic pumping. Worms are observed to have an 90 to 180 degree twist along the their bodies.

    Movement in the Tube: When the worm is partially out of its tube, it moves up and down by a method referred to as paella walking.

    Connection to the Tube: The worm is able to remain in the tube through the use of uncirigerous tori. These tori are placed so that water flow is still efficient throughout the tube.

    Feeding Behavior: When the worm is actively feeding, ciliary currents are observed throughout the tube. These currents are due to transverse bands of cilia along the dorsal surface, as well as cilia long the lateral body.

    Defecation: The worm is able to defecate by using peristaltic waves that move from the cauda to the abdomen. The fecal matter is passed to the posterior margin of the ventral plate where the feces is expelled from the tube.