Sabellaria spinulosa
Encyclopedia
Sabellaria spinulosa is a species
of marine polychaete
worm in the family
Sabellariidae
, commonly known as the Ross worm. It lives in a tube built of sand, gravel and pieces of shell.
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.
, in the sublittoral zone
and occasionally in the intertidal zone. It is also found in other regions of the north east Atlantic Ocean south to Portugal
and the Mediterranean Sea
.
, 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
, spawning
mostly takes place between January and March and the larva
e became part of the zooplankton
. Development of the larvae take 4 to 8 weeks before they settle and undergo metamorphosis
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. Shells of the scallop Pecten maximus
also attracted larvae to a lesser extent. Larvae of S. alveolata were attracted to settle near adult S. spinulosa but not vice versa.
habitat for a large number of invertebrate
s and juvenile fish. They are often dominated by the presence of crustacean
s, especially the porcelain crab (Pisidia longicornis
) and the pink shrimp (Pandalus montagui
), which feed on the worms and on other invertebrates which shelter in the reefs. Another frequent resident is the queen scallop (Aequipecten opercularis
).
The reefs are at risk from trawling and other human activities that disturb the seabed. For example, in the Wadden Sea
, trawling for pink shrimp (Pandalus montagui) broke up the reefs and destroyed the fishery as well.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of marine 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...
worm in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Sabellariidae
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 detrivores.-Characteristics:...
, commonly known as the Ross worm. It lives in a tube built of sand, gravel and pieces of shell.
Description
S. 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 operculumOperculum (animal)
An operculum is an anatomical feature, a stiff structure resembling a lid or a small door that opens and closes, and thus controls contact between the outside world and an internal part of an animal...
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.
Distribution
S. spinulosa is found round the coasts of the British IslesBritish Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
, in the sublittoral zone
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
and occasionally in the intertidal zone. It is also found in other regions of the north east Atlantic Ocean south to Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
and the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
.
Biology
S. spinulosa is a filter feederFilter feeder
Filter feeders are 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 feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
, 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
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...
, spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
mostly takes place between January and March and 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 became part of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
. Development of the larvae take 4 to 8 weeks before they settle and undergo metamorphosis
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
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. Shells of the scallop Pecten maximus
Pecten maximus
Pecten maximus, common name the "great scallop" or "king scallop", is a species of scallop, an edible saltwater clam, a marine bivalve mollusc in the family Pectinidae, the scallops.This is the type species of the genus....
also attracted larvae to a lesser extent. Larvae of S. alveolata were attracted to settle near adult S. spinulosa but not vice versa.
Ecology
S. 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. 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 biodiverseBiodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
habitat for a large number of invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s and juvenile fish. They are often dominated by the presence of crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, especially the porcelain crab (Pisidia longicornis
Pisidia longicornis
Pisidia longicornis, the long-clawed porcelain crab, is a species of porcelain crab that lives in the north-eastern Atlantic Ocean. It varies from reddish to white, and grows to a carapace width of . It was first named by Carl Linnaeus in 1767, although the etymology remains...
) and the pink shrimp (Pandalus montagui
Pandalus montagui
Pandalus montagui is a species of cold water shrimp in the family Pandalidae. It is the type species in the genus Pandalus and is variously known as the pink shrimp, Aesop shrimp and Aesop prawn.-Description:...
), which feed on the worms and on other invertebrates which shelter in the reefs. Another frequent resident is the queen scallop (Aequipecten opercularis
Queen scallop
The Queen Scallop, scientific name Aequipecten opercularis, is a medium-sized species of scallop, an edible marine bivalve mollusk in the family Pectinidae, the scallops.-Description:...
).
The reefs are at risk from trawling and other human activities that disturb the seabed. For example, in the Wadden Sea
Wadden Sea
The Wadden Sea is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern continental Europe and the range of Frisian Islands, forming a shallow body of water with tidal flats and wetlands. It is rich in biological diversity...
, trawling for pink shrimp (Pandalus montagui) broke up the reefs and destroyed the fishery as well.