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Polychaeta

The word Polychaeta means many bristles. This feature is obvious on many polychaetes, but others have either very small or cryptic bristles or have lost them entirely. Polychaetes are the most complex of the annelids in body construction and are very common in the oceans, especially on or in sandy and muddy bottoms, where they may make up more than 50% of the larger metazoan fauna. The longest of all known polychaetes was found in Port Jackson, Australia. It was a member of the family Eunicidae, consisted of approximately 1,500 segments and was nearly 6 meters long when alive.

  1. Phyllodocidae (paddle worms):coralPhyllodoce longipes

    The phyllodocids are named for the flattened dorsal cirri, which cover the body like tiles on a roof. These worms are hunting predators adept at following mucus trails laid down by worms and small crustaceans crawling around on the surface. Image copyright SFBay:2K, California Academy of Sciences.

  2. Maldanidae (bamboo worms): coral Sabaco elongatus

    The bamboo worms get their common name from their very long body segments. They live in tubes in sand and mud, sitting head-end down and feeding on contained organic particles in the mud. Image copyright SFBay:2K, California Academy of Sciences.

  3. Polynoidae (scale worms):coralAsterophilia culcitaecoralAsterophilia culcitae

    These two specimens of the same species are commensals living on differently colored starfish. Image copyright Timor Britayev, Akademia Nauk, Moscow

  4. Polynoidae (scale worms):Chaetacanthus magnificus

    The characteristic scales are modifications of the dorsal cirri common in many polychaetes. The scales may cover the body so completely that only the tips of the antennae and other head appendages can be seen. Many of the scale worms are commensals with other invertebrates. Image copyright Arthur Anker, STRI

  5. Sabellidae (fan worms):coralBispira sp.

    The fan worms trap particles suspended in the water using the cilia along the edge of the large tentacular crown (the fan). Image copyright SFBay:2K, California Academy of Sciences.

  6. Terebellidae (spaghetti worms):coralNeoamphitrite robusta

    The spaghetti worms live in tubes. Normally, the only part of the worm visible outside the tubes are the extremely mobile tentacles used for feeding. These tentacles are left alone by predators, because they are extremely distasteful. Image copyright SFBay:2K, California Academy of Sciences.

  7. Glyceridae (blood worms):coralUnidentified Glyceridae

    The blood worms live in tunnels in sand and mud. They have an enormous proboscis tipped with two pairs of hollow jaws which they use to inject a neurotoxin into their prey. These worms are often used as live bait. Image copyright Dr. Paul K. S. Shin, City University of Hong Kong.

  8. Sternaspidae: coralSternaspis scutata

    The shield covering the ventral posterior end is a very unusual structure among the polychaetes. Located near the anterior end (left) is a pair of nephridia (kidneys). Further left is the head, which can be retracted completely. Image copyright Dr. Paul K. S. Shin, City University of Hong Kong.

  9. Cirratulidae: coralUnidentified Cirratulidae

    The cirratulids are present in all kinds of environments down to the greatest depths of the ocean. The whitish tentacles are used to collect food, transporting small particles to the mouth with ciliary action. The reddish structures further back along the body are branchiae. The red color is caused by the presence of hemoglobin, a respiratory pigment resembling the one present in humans. Image copyright Dr. Paul K. S. Shin, City University of Hong Kong.

  10. Syllidae: coralMyrianida pachycera

    The syllids are among the most common and species-rich groups of polychaetes present in shallow water. This specimen is undergoing asexual reproduction. Each of the small sections will eventually break off to become a separate individual. Image copyright, Dr. Greg Rouse, Scripps Institution of Oceanography

  11. Pectinariidae
    (ice cream cone worms): coralLagis sp.

    The ice cream cone worms are best known for their conical, neatly structured tube. This picture shows the specimen which lives inside the cone. The front end (on the left) carries two heavy, brass or copper colored sets of spines used to burrow through the sediment. Image copyright Dr. Paul K. S. Shin, City University of Hong Kong.

  12. Eunicidae: coralEunice aphroditoiscoral Marphysa sanguinea

    The eunicids are especially common in coral reef environments where they burrow into dead coral with a complex system of jaws. Very similar jaws are present in the fossil record, back to the Ordovician (ca. 400 million years ago), and identical jaws are present in 200 million years old fossil strata. Image copyright Jeffrey Rosenfeld, The Vibrant Sea. Image copyright SFBay:2K, California Academy of Sciences.

  13. Nereididae (rag worms): coralNereis succinea

    The rag worms have a large eversible proboscis, tipped with a pair of curved jaws and most often with small, black triangular teeth covering the outside of the proboscis. They use their jaws mainly to fight each other, since they are usually territorial, but they can also use their jaws for feeding. Image copyright Leslie Harris, Natural History Museum of Los Angeles County.

  14. Amphinomidae (fireworms): Hermodice carunculata

    The fireworms are colorful, slow-moving and are often seen crawling around on corals and sea anemones. The bristles (white in the picture) are hollow, brittle and break off easily when the worm is touched. When broken, the bristles inject a highly acidic irritant into the wound, causing a nasty infection. Image copyright Chuck Savall.

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