Spirorbis corallinae
Encyclopedia
Spirorbis corallinae is a very small (1-2 mm
) coiled polychaete
that lives attached to seaweed
in shallow saltwater.
It has a smooth, white or semi-translucent, sinistral
(left-handed) coiled shell encasing an orange body about 1.5 mm in length.
The worm has a short abdominal region and a slightly broader thorax
terminating in colourless tentacles, used to filter food from the water. One of the tentacles is slightly larger than the rest and shaped like a saucer, which is used as an operculum
. This seals the opening of the shell and serves to protect the worm from predators and desiccation
when out of water.
It lives primarily on the red algae Corallina officinalis
, after which it takes its name, but is also known to live on Irish Moss
(Chondrus crispus). The shell is often confused with the white growing tips of Corallina fronds.
The Spirorbis genus
are cross fertilising hermaphrodites, who brood their young in a tube attached to the worm inside the shell. The larva
e are released at an advanced stage of development and spend just a few hours as free-living organsisms before attaching themselves to the nearest suitable surface, often the same seaweed as the parent.
, north and west coasts of Britain
; also the coast from North Norway
to North France
.
Millimetre
The millimetre is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length....
) coiled 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...
that lives attached to seaweed
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
in shallow saltwater.
It has a smooth, white or semi-translucent, sinistral
Sinistral
Sinistral and dextral are scientific terms that describe chirality or relative direction in a number of disciplines.The terms are derived from the Latin words for “left” and “right” ....
(left-handed) coiled shell encasing an orange body about 1.5 mm in length.
The worm has a short abdominal region and a slightly broader thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
terminating in colourless tentacles, used to filter food from the water. One of the tentacles is slightly larger than the rest and shaped like a saucer, which is used as an operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
. This seals the opening of the shell and serves to protect the worm from predators and desiccation
Desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...
when out of water.
It lives primarily on the red algae Corallina officinalis
Corallina officinalis
Corallina officinalis is a calcareous red seaweed which grows in the lower and mid-littoral zones on rocky shores.It is primarily found growing around the rims of tide pools, but can be found in shallow crevices anywhere on the rocky shore that are regularly refreshed with sea water...
, after which it takes its name, but is also known to live on Irish Moss
Irish moss
Chondrus crispus, known under the common name Irish moss, or carrageen moss , is a species of red algae which grows abundantly along the rocky parts of the Atlantic coast of Europe and North America...
(Chondrus crispus). The shell is often confused with the white growing tips of Corallina fronds.
The Spirorbis genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
are cross fertilising hermaphrodites, who brood their young in a tube attached to the worm inside the shell. 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 released at an advanced stage of development and spend just a few hours as free-living organsisms before attaching themselves to the nearest suitable surface, often the same seaweed as the parent.
Distribution
IrelandIreland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, north and west coasts of Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
; also the coast from North Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
to North France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
.