Paralvinella palmiformis Desbruyères & Laubier 1986

How to Distinguish from Similar Species: Of other species that may be found at Pacific Northwest hydrothermal vents, P. pandorae has only about 60 chaetigerous segments and only the first 3 chaetigerous segments have only notopodia. It is light brown to pink in alcohol. P. sulfincola has only about 54-68 chaetigerous segments, and the first 24-30 have only notopodia. Its body doesn't taper much until the last 10 segments. It may turn chocolate brown when preserved in formalin.

The sulfide chimneys of hydrothermal vents.

Geographical Range: Deep-sea hydrothermal vents in the NE Pacific: Gorda Ridge, Explorer Ridge, Juan de Fuca Ridge

Depth Range: Deep sea, about 2000 m

Order Canalipalpata are the bristle-footed Annelids or fan-head worms. They have no jaws or teeth. Most have grooved, ciliated tentacles with which they feed. Terebellids are mostly sessile tubeworms. Family Alvinellidae is found in the deep sea at hydrothermal vents. They usually build mucus tubes and feed with flattened, ciliated tentacles, plus obtain nutrition from episymbiotic bacteria living on their surface. Paralvinella palmiformis has a body with 100-118 segments, which gradually taper posteriorly. The prostomium is reduced in its middle portion. A set of many smooth, grooved tentacles forms the buccal apparatus. Males also have two robust peribuccal tentacles that end in three rounded lobes bordered with papillae, and two blind cavities on the ventral side of the peristomium. The featherlike branchiae fan out anteriorly, dorsal to the feeding tentacles. The first 20-31 chaetigerous segments have only notopodia, and segment 7 is highly modified. Color pinkish when preserved in alcohol, brownish red in life. Length up to 8 cm.

Biology/Natural History: Typically live with caudal end coiled around other worm tubes or attached to the surface of sulfide chimneys. They are a deposit feeder and cover themselves with mucus. Paralvinellids also are symbiotic with ectosymbiotic bacteria which live on the mucus. Can withstand rather high temperatures, but not as high as its congener P. sulfincola can. At its highest temperatures it increases heat-shock protein levels. Glycine is the major osmolyte, and it contains less thiotaurine, which may be used in sulphide detoxification, than does P. sulfincola. The species contained no sarcosine. Aerobic metabolism appears to dominate in the gills, while anaerobic metabolism appears to be more prominent in the body wall.