# Polychaete

A polychaete (or bristle worm) is a member of the class Polychaeta. This class, with about 85 known families, belongs to the phylum Annelida (segmented worms) and generally consist of marine worms. In the class Polychaeta, more than 11,000 species and 1400 genera have been scientifically described. Polychaetes are found in nearly every marine habitat, occupy a wide variety of ecological niches, and constitute the majority of the species belonging to the annelid phylum. Less than 2% of the known species in the class Polychaeta live in fresh water. Most of the polychaete species burrow in sediments or live under rocks in the sea.

## Quotes

* ... I spent several hours in exploring Mew Island, a little coral islet near the entrance of the Sundra Strait This island is densely wooded to the water's edge, and is partly encircled by a barrier-reef. As I stepped from the boat upon the reef, I was struck at once with the extreme beauty of a species of amphitrite, a sea-worm living in holes of the great solid madrepores which compose the reef. The gills of these lovely creatures are in the form of spiral ribbons of a brilliant orange-green and blue; these resplendent gaudy plumes are alternately extruded and withdrawn, and seen through the pellucid water, present a very singular and beautiful appearance
** Arthur Adams, Travels of a Naturalist in Japan and Manchuria. Hurst and Blackett. 1870. p. 51. The English sailors used the name “Mew Island” for the Dutch-named Meeuwen-eiland (Seagull Island, in translation).
* ... Alien polychaete species in the Mediterranean Sea mostly originated from the Red Sea and Indo-Pacific areas. Benthic habitats of the areas between 40°N and 40°S were colonized by polychaetes mostly originating from other tropical and subtropical regions. The Suez Canal and shipping are the major vectors for species introductions. Some species imported and exported as fishing baits have become established at non-native localities. The invasive polychaete species have greatly altered habitat structures in some areas, restructured the food webs, and created important economic problems.
** Melih Ertan Çinar, (August 2013)"Alien polychaete species worldwide: current status and their impacts". Journal of the Marine Biological Association of the United Kingdom 93 (5): 1257–1278. DOI:10.1017/S0025315412001646.
* … with polychaetes ... there is a huge variety of colors and shapes and behaviors. Some spend their entire lives swimming in the ocean like fish. Some are so big that they can actually catch and eat fish as big as a foot long. You've got ones that have feeding tentacles that look like spaghetti, and we call them spaghetti worms. We've got carnivores that eat meat. We've got herbivores that will only eat vegetation like seaweed and other types of algae. We've got ones that make tubes and amazing structures that they live in.
** Leslie Harris, (November 23, 2020)"Meet the Scientist: Leslie Harris, Polychaetes". Natural History Museum of Los Angeles County (NHM), YouTube. (quote at 2:20 of 25:45)
* Most polychaetes have some type of photoreceptor or eyes. Eyes are generally located on the prostomium. The complexity of eyes varies from simple pigment cups or ocelli, to well developed camera-type eyes, to compound eyes analogous to those found in arthropods (Eakin and Hermans 1988). Ocelli occur in a wide range of polychaete taxa. They can be as simple as two cells—a sensory cell and a pigmented support cell ... Other forms of ocelli are more complex but still may be composed of only a few dozen cells. They probably perceive information about light direction and intensity. In certain Phyllodocica, particularly the swimming predatory Alciopini, the eyes are probably capable of forming an image. The eyes of Alciopini can be up to a millimetre across and so large that they protrude laterally from the head and press into the brain. They consist of a primary retina containing thousand of cells, a secondary retina overlain by a lens and other accessory structures (Hermans and Eakin 1974). Compound eye, which evolved independently of those of arthropods, are found on the radiolar crown of some Sabellidae ...
** Gregory Rouse and Fredrik Pleijel, "Chapter 3. Polychaete Anatomy. Eyes". Polychaetes. Oxford University Press. 2001. p. 28. ISBN 0198506082.

## See also

* Glowworms
* Worms

## External links

* Media related to Polychaeta on Wikimedia Commons
* The dictionary definition of polychaete on Wiktionary