''Spirorbis corallinae'' is a very small (1-2
mm) coiled
polychaete (bristle worm) that lives attached to
seaweed
Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...
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
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
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
Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.
...
when out of water.
It lives primarily on the red algae ''
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 shor ...
'', after which it takes its name, but is also known to live on Irish Moss (''
Chondrus crispus
''Chondrus crispus''—commonly called Irish moss or carrageen moss (Irish ''carraigín'', "little rock")—is a species of red algae which grows abundantly along the rocky parts of the Atlantic coast of Europe and North America. In its fresh c ...
''). 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
larvae are released at an advanced stage of development and spend just a few hours as free-living organisms before attaching themselves to the nearest suitable surface, often the same seaweed as the parent.
Distribution
Ireland, north and west coasts of
Britain; also the coast from
North Norway to
North France.
External links
General spirorbid morphology
Serpulidae
Animals described in 1962
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