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 marine
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 in the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Sabellariidae
Sabellariidae is a family of marine polychaete worms in the suborder Sabellida. The worms live in tubes made of sand and are filter feeders and detritivores.
Characteristics
Members of this family live in tubes made of sand and shell fragments c ...
, commonly known as the Ross worm. It lives in a tube built of sand, gravel and pieces of shell.
Description
''Sabellaria spinulosa'' lives in a tube made of shell fragments and coarse sand cemented together with mucus. The tube has a circular cross section and can be closed by an operculum formed by bristles growing on the head of the worm. There are several thoracic segments and the abdomen has many segments that have hooked bristles on raised lobes. The worm's distinguishing features include three thoracic segments with paired chaetal sheaths, pointed opercular chaetae and an outer layer of serrated chaetae.Ross worm - ''Sabellaria spinulosa''.
Marine Life Information Network The Marine Life Information Network (MarLIN) is an information system for marine biodiversity for Great Britain and Ireland
Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic O ...
. Retrieved 2011-11-03.
Distribution
''Sabellaria spinulosa'' is found round the coasts of the
British Isles
The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...
, in the
sublittoral zone
The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth.
From the point of view of marine biology it forms a relatively stable and well-illuminated ...
and occasionally in the intertidal zone. It is also found in other regions of the north east Atlantic Ocean south to
Portugal
Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
and the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
.
Biology
''Sabellaria spinulosa'' is a
filter 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 ...
, extending its feeding tentacles to catch plankton and detritus that are brought within its reach by the current. Individual worms are either male or female. In the
English Channel
The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" (Cotentinais) or ( Jèrriais), (Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kana ...
,
spawning
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...
mostly takes place between January and March and the
larva
A larva (; plural larvae ) 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.
The ...
e became part of the
zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
. Development of the larvae take 4 to 8 weeks before they settle and undergo
metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
and start building tubes. The worms live for 2 to 5 years, or possibly for as long as 9 years.
The worms are very tolerant of adverse conditions such as polluted water, low salinity or low oxygen levels. They favour localities where currents or waves churn up sand but they need a hard substrate to get established. The larvae are strongly attracted to settle in areas where adults are already living or other larvae have settled, but if, after 2 months, the larvae have not found such a place, they settle independently.Wilson, D.P. 1970. The larvae of ''Sabellaria spinulosa'' and their settlement behaviour, Journal of the Marine Biological Association of the United Kingdom, 50, 33-52. Shells of the scallop ''
Pecten maximus
''Pecten maximus'', common names the great scallop, king scallop, St James shell or escallop, is a northeast Atlantic species of scallop, an edible saltwater clam, a marine bivalve mollusc in the family Pectinidae. This is the type species of th ...
'' also attracted larvae to a lesser extent. Larvae of ''S. alveolata'' were attracted to settle near adult ''S. spinulosa'' but not vice versa.
Ecology
''Sabellaria spinulosa'' usually lives singly in a tube attached to the substrate over its entire length. In much of its range it does not forms reefs in the same way as the closely related honeycomb worm, ''
Sabellaria alveolata
''Sabellaria alveolata'', (also known as the honeycomb worm), is a reef-forming polychaete. It is distributed around the Mediterranean Sea, and from the north Atlantic Ocean to south Morocco. It is also found in the British Isles at its norther ...
''. When the worms are crowded together the tubes may stand up vertically and form crusts or mounds several metres across. Unaggregated individuals may reach densities of 300 per square metre (10sq ft), and densities of 4000 individuals per square metre have been recorded in loose aggregations. However, under a narrow set of environmental circumstances, reefs are formed. These include: sand or gravel sea floor, the edges of sandbanks, the edges of channels and drop-offs, high turbidity, high sediment load, moderate currents and moderate suspended organic particulate load. Where reefs exist, they provide a
biodiverse
Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') ...
habitat for a large number of
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s and juvenile fish. They are often dominated by the presence of
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s, especially the porcelain crab ('' Pisidia longicornis'') and the pink shrimp (''
Aequipecten opercularis
The queen scallop (''Aequipecten opercularis'') is a medium-sized species of scallop, an edible Marine (ocean), marine bivalve mollusk in the family Pectinidae, the scallops. It is found in the northeast Atlantic and is important in fisheries.
D ...
'').
The reefs are at risk from trawling and other human activities that disturb the seabed. For example, in the
Wadden Sea
The Wadden Sea ( nl, Waddenzee ; german: Wattenmeer; nds, Wattensee or ; da, Vadehavet; fy, Waadsee, longname=yes; frr, di Heef) is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern conti ...
, trawling for pink shrimp (''Pandalus montagui'') broke up the reefs and destroyed the fishery as well.''Sabellaria spinulosa'' reefs. UK Biodiversity Action Plan. Retrieved 2011-11-03.