Eudistylia polymorpha

Geographic Range

E. polymorpha can been spotted all along the Pacific Coast from Alaska to San Pedro. It is especially common in the Pacific Grove. (Ricketts, et al 1985)


E. polymorpha lives in its translucent greyish, tannish tube that is attached to rocks, pilings, harbors, floats, and wharves along the Pacific coast. This tube is often encrusted with bits of shell or sand. They anchor the tubes deep into the rocks to prevent "uprooting" and it is known to take a great deal of effort to pry an entire animal froms its location. Some have even been found anchored in sponges.

They may be found near the low-tide line to water 1400 feet deep. However, more often they inhabit tide pools in large numbers giving the appearance of a flower garden. (Snook and Johnson, 1967; McConnaughey and McConnaughey, 1986)

Physical Description

The Giant Feather Duster Worm is usually 10" long and about 1/2" wide. The body of E. polymorpha is encased in a translucent, tannish tube which is often encrusted with sand and bits of shell. Its large plume of 30 feather like gills on each side of the tube is 2 1/2" across when expanded. They may be maroon, reddish, orange, or brown and usually have cross bands of lighter and darker shades. The gills have numerous eyespots which aid them in sensing when to retract into their tubes.

There are two key characteristics in distinguishing E. polymorpha from E. vancoveri, a very similiar organism and possible hybridizing partner. The dorsal edge of the the branchial crown of E. polymorpha is deeply cleft, and the gills are usually deep maroon with orange tips. On E. vancoveri the gills are red with white tips and the crown has no cleft. (Snook and Johnson, 1967; Ricketts, et al 1985; McConnaughey and McConnaughey 1986)


Fertilization is external. The anatomy of the reproductive system includes gonads that are in back of the abdomen, bulging into the anterior part of the coelomic compartments, and two ciliated gonoducts which exit the coelom of each segment and open ventrally via gonopores near the abdominal fecal groove. Gametes accumulate in the coelomic spaces of the abdomen where they mature.

When mature, gametes enter the gonoducts, leave via the gonopores and are carried forward by cilia of the fecal groove. Palps with cilia, next to the first branch of each brachial stalk, transport gametes from the fecal groove to be released into the sea.

Sperm receptacles are known to occur at the base of crown tentacles in females of three species. In addition, free spawning also occurs in which individuals produce oocytes 140-200 um in diameter. (Brooding species produce oocytes over 200 um in diameter.) These are deposited in gelatinous masses on the tube or on sediment surface and are retained in a membraneous capsule tube.

Development to non-feeding pelagic trochophores and setigerous (segmented) larva is rapid. Settlement occurs in three to four weeks.

Many individuals have been found with characteristics of both E. polymorpha and E. vancoveri, implying that hybridization between the two species may occur.

(Fox 1994; Strathmann, 1987)


E. Polymorpha is a colonial animal living in large groups in tide pools. They are passive animals and not very motile. However, their eyespots on their gills alert them of danger and they are best known for their remarkable quickness of retracting their gills back into their tubes. This "shadow reflex" occurs when they are touched or a shadow passes over them. (McConaughey and McConnaughey, 1986; Snook and Johnson, 1967)

Food Habits

E. polymorpha is a member of the family Sabellidae which are suspension feeding polychaetes. These animals are active suspension feeders in that they create a current to direct food particles. Their location in moving water is vital to their survival because the current must bring a continous flow of food particles.

The network used to direct these food particles begins with spiral bundles of pinnately branched, ciliated branchiaeon arising in a row around the branchial stalk. These are located on each side of the head. Posterior to the two branchial stalks is a large funnel-like mouth. The branchiae groove is responsible for transporting food to the mouth in that it leads to a large stalk groove that spirals down the brachial stalk and empties into the mouth.

Food collected by the meshwork of ciliated pinnules is sorted and transported to the mouth by this system of grooves. These pinnules have a groove on their medial surface with two types of cilia that further aid in capturing food by creating a feeding current. These cilia also lead food to the branchial groove on the branchial axis.

In the digestive system of the E. polymorpha, a gut tube which fills most of the space in the coelem, includes the mouth and anus. Its epithelium is ciliated. The stomach epithelium is ciliated and has secretory cells, but the intestine lacks these. (Fox, 1994)

Economic Importance for Humans: Positive

E. Polymorpha is a special delight to scuba divers and snorkelers of the Pacific Coast. This is also an easy species to dissect to learn more about the Phylun Annelida. This worm has a few variations from the regular segmented worms that may make it interesting to those studing invertebrate anatomy. (Fox, 1994)

Economic Importance for Humans: Negative

E. polymorpha has adapted its habitat to fit wharves, harbors, and floats along the Pacific Coast. The worms' habit of adhering to these man-made structures could be bothersome to marine workers. These worms are also considerably hard to remove, anchoring deep in crevices of their substrate; it has been thought that "one might need the help of a crow bar to pry the enitre animal from its ground." (Snook and Johnson, 1967)

Conservation Status

Other Comments

To see a great picture of Eudistylia polymorpha go to

or to this site


Suzanne McGaugh (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.


Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


the nearshore aquatic habitats near a coast, or shoreline.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.


Fox, .. 1994. "Invertebrate Anatomy: Eudistylia vancouveri" (On-line). Accessed Feb. 18, 2000 at

McConnaughey, .., .. McConnaughey. 1986. Audubon Society Nature Guides. New York: Alfred A. Knopf Inc..

Ricketts, .., .. Calvin, .. Hedgpeth. 1985. Between Pacific Tides. Stanford, California: Stanford University Press.

Snook, .., .. Johnson. 1967. Seashore Animals of the Pacific Coast. New York, NY: Canada General Publishing Company.

Strathmann, .. 1987. Reproduction and Development of Marine Invertebrates of the Northern Pacific Coast. Settle, Washington: University of Washington Press.