Eudistylia polymorpha, the giant feather duster worm, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of marine polychaete

Polychaete

The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...

 worm

Worm

The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

 belonging to the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Sabellidae

Sabellidae

Sabellidae are sedentary marine polychaete tube worms where the head is mostly concealed by feathery branchiae. They build tubes out of parchment, sand, and bits of shell...

. It receives its common name from the crown of tentacles that are extended when the animal is underwater.

Description

E. polymorpha has a body up to 25 cm (10 in) long and 1.2 cm (0.5 in) thick and lives within a tube. This is parchment-like and composed of sediment cemented with mucus

Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

. It is a brownish colour, translucent and often strengthened with sand and shell fragments. On rocky shores it may be hidden in a crevice and be difficult to dislodge. The branchia

Branchia

Branchia may refer to:* Branchia, an Ancient Greek word for gills.* Branchia , a genus of arthropods....

e (feeding appendages) in the feathery crown also function as gills. They are also known as radiole

Radiole

A radiole is a heavily ciliated feather-like tentacle found in highly organized clusters on the crowns of Canalipalpata. Canalipalpata is an order of sessile marine polychaete worms consisting of 31 families...

s and are a shade of red or brown, banded with paler sections. Shades vary but the most frequent colouration is maroon with orange tips. They arise from two spiral, deeply cleft, bases. They bear eyespots which alert the worm to sudden shadows or movements nearby. This enables the crown to be retracted into the tube very rapidly when danger threatens. The posterior segments of the worm bear hooked bristles which help anchor it in its tube. E. polymorpha can be distinguished from the very similar Eudistylia vancoveri by the cleft in the crown. Also E vancoveri generally has red branchiae with white tips.

Distribution and habitat

The range of E. polymorpha extends down the western seaboard of North America, from Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 to California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. It is found in the intertidal zone

Intertidal zone

The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...

 in tide pool

Tide pool

Tide pools are rocky pools by oceans that are filled with seawater. Many of these pools exist as separate entities only at low tide.Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biologists, as well as philosophical...

s and in the neritic zone

Neritic zone

The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...

 at depths of up to 420 metres. It tends to grow in groups and can be found growing on rocks, reefs, pilings, wharves and marinas.

Biology

E. polymorpha is a filter feeder

Filter feeder

Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...

, catching food particles with its pinnately branched radioles. It prefers to live in moving water in order that a constant stream of particles come within reach. These are trapped by the feeding appendages and moved by cilia down grooves in the radioles to the large, funnel-shaped mouth. The gut takes up most of the coelom

Coelom

The coelom is a fluid-filled cavity formed within the mesoderm. Coeloms developed in triploblasts but were subsequently lost in several lineages. Loss of coelom is correlated with reduction in body size...

 space and there is a faecal groove for ejection of undigested debris. Any particles that are too large to be ingested get incorporated into the tube structure.

Reproduction takes place in the spring and fertilisation is external. The gonad

Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes...

s are on the dorsal side of the abdomen and the gametes mature in the coelomic spaces. They are then passed forward by cilia along the faecal groove and are released into the water column. The larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e are plankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

ic and grow rapidly. After about three or four weeks they settle out as segmented larvae.