''Spirorbis borealis'' is a sedentary marine
polychaete worm in the
Serpulidae family. It is commonly called the sinistral spiral tubeworm and is the
type species of the genus ''Spirorbis''.
Polychaetes, or marine bristle worms, have elongated bodies divided into many segments. Each
segment may bear
setae (bristles) and
parapodia (paddle-like appendages). Some species live freely, either swimming, crawling or burrowing, and these are known as "errant". Others live permanently in tubes, either calcareous or parchment-like, and these are known as "sedentary".
Description
''S. borealis'' secretes a very small, unridged, off-white, calcareous tube. This is about five millimetres in diameter and forms a flat, clockwise spiral coil as seen from above. The worm retreats into its tube when above water but under water can be seen to have green tentacles.
[John Barrett and C M Young, Collins Pocket Guide to the Sea Shore (1958) p.76]
Distribution and habitat
''S. borealis'' is found on either side of the north Atlantic Ocean. This includes the coasts of
Great Britain,
Ireland,
Spain and
Portugal,
Prince Edward Island,
Newfoundland
Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
, the
Gulf of St Lawrence
, image = Baie de la Tour.jpg
, alt =
, caption = Gulf of St. Lawrence from Anticosti National Park, Quebec
, image_bathymetry = Golfe Saint-Laurent Depths fr.svg
, alt_bathymetry = Bathymetry ...
and the St Lawrence estuary.
[
It is typically found growing on '' Fucus'', '' Laminaria'' and other seaweeds as well as on rocks and stones. It is widely distributed and abundant on the middle and lower shore,][ down to a depth of about thirty metres.][
]
Biology
''S. borealis'' is a hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.
Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...
. The segments at the front of the abdomen are female while those at the back are male.[ The male and female ]gonad
A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...
s mature at much the same time but the sperm is usually released first. Fertilisation is external to the body but inside the tube. The larvae are free swimming member of the plankton for a short time. They then settle out. In a study, where fronds of ''Fucus serratus'' already colonised by adults were available for settling, the larvae avoided the most densely populated areas and favoured the concave grooves on either side of the midribs. When prevented from settling out for eight hours, they were much less selective and settled on any ''Fucus'' surface regardless of the presence of adults.Observations on the Settling Behaviour of Larvae of the Tubeworm ''Spirorbis borealis'', Daudin (Polychaeta)
/ref>
References
{{Taxonbar, from=Q2765832
Serpulidae
Animals described in 1800