''Lanice conchilega'', commonly known as the sand mason worm, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of burrowing

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

polychaete Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...

worm. It builds a characteristic tube which projects from the seabed, consisting of cemented sand grains and shell fragments with a fringe at the top. Polychaetes, or marine bristle worms, have elongated bodies divided into many segments. Each segment may bear

setae In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

(bristles) and

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...

(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

''L. conchilega'' can grow up to thirty centimetres long with as many as three hundred segments. It has an elongated body divided into two parts. The head bears a dense tuft of long, thin

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s. The upper lip is narrow and encloses the mouth. The buccal segment has protruding lobes laterally and ventrally and there are many eye spots. Segments 2 to 4 bear branching

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

s with broad stems and a thick crown. The third segment has a large lobe that obscures the second segment. Posterior to these, the thoracic region consists of seventeen segments and is cylindrical and firm. There are glandular pads on the ventral sides of segments 14 to 20 which bear both hair-like and hooked chaetae. The long, slender abdomen is soft and bears only hooked chaetae. The worm is yellowish, pink or brown with pale-coloured tentacles and red gills.Marine Species Identification Portal
/ref>

Distribution and habitat

''L. conchilega'' is found in the northern hemisphere in many parts of the world. It is found living in soft sediments, sand or muddy sand and among ''

Zostera ''Zostera'' is a small genus of widely distributed seagrasses, commonly called marine eelgrass, or simply seagrass or eelgrass, and also known as seaweed by some fishermen and recreational boaters including yachtsmen. The genus ''Zostera'' con ...

'' and benthic

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

. It is tolerant of low salinity and is found in the eulittoral zone and at depths down to 1700 metres.

Biology

''L. conchilega'' lives in a straight tube composed of large sand grains and shell fragments cemented with

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

that protrudes several centimetres from the surface of the sediment. The long tentacles protrude from the top searching for food particles and are supported by the fringe-like rim of the tube. The worm can retreat rapidly into the tube if danger threatens, and can extend the tube if it becomes buried in shifting sediment. This worm can be found as a few scattered individuals or in populations of several thousand per square metre. Buhr and Winter considered it likely that at low densities, the worm is predominately a

detritivore Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...

, feeding on organic particles such as

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...

ns,

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

and the faeces of

echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea ...

s and

molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil sp ...

. At higher densities, it is more likely to be a

suspension feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

, feeding on

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

and other organic particles floating in the

water column A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...

. Individual mason worms are either male or female and breeding occurs in spring and summer in the northern hemisphere. The larvae remain suspended in the plankton for about two months and during that time may become widely dispersed.Marine Life Information Network
/ref> After about five days, each larva starts to form a tube of slime and detritus, in which it develops further, and by the time it is sixty days old and ready to settle, it has twelve to fourteen thoracic segments.

Ecology

Large congregations of the mason worm can be considered as

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

-building. Patches of tubes influence the

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

structure and are of consequence for the distribution and abundance of other species living under the seabed. ''L. conchilega'' is part of the diet of a number of wading birds and of young flat fish.Vanaverbeke J., U. Braeckman, S. Claus, W. Courtens, N. De Hauwere, S. Degraer, K. Deneudt, A. Goffin, J. Mees, B. Merckx, P. Provoost, M. Rabaut, K. Soetaert E. Stienen and M. Vincx (2009). Analysis of long-term data from the Belgian Continental Shelf in the framework of science-based management of the coastal North Sea. Workshop Report WestBanks, Oostende 29/10-31/10/2008.

References

{{Taxonbar, from=Q1019295 Terebellida Animals described in 1766 Taxa named by Peter Simon Pallas