honeycomb worm
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''Sabellaria alveolata'', (also known as the honeycomb worm), is a reef-forming
polychaete Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...
. It is distributed around 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 ...
, and from the north
Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
to south
Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria t ...
. It is also found in 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, ...
at its northern limit in the northeast Atlantic. Its common name is derived from the
honeycomb A honeycomb is a mass of hexagonal prismatic wax cells built by honey bees in their nests to contain their larvae and stores of honey and pollen. Beekeepers may remove the entire honeycomb to harvest honey. Honey bees consume about of honey ...
-like pattern it creates when building its tube reefs.


Description

''Sabellaria alveolata'' is an annelid (ringed worm) that lives in small tubes it constructs from cemented coarse sand and/or shell material, forming
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 o ...
s. The tubes are arranged in close proximity and have a distinctive honeycomb-like appearance. These reefs range from to thick and take the form of hummocks, sheets or more massive formations. Adult size ranges from . The
thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
has three pairs of flattened chaetal sheaths, its chaetes form an operculum which is used to seal the tube opening. Depending on the local substrate, the colour of the tube varies.


Distribution

''Sabellaria alveolata'' is found in the Mediterranean and the north Atlantic from Britain south to Morocco. In Britain and Ireland it is mainly found in inter-tidal zones along southern and western coasts from the
Western Isles The Outer Hebrides () or Western Isles ( gd, Na h-Eileanan Siar or or ("islands of the strangers"); sco, Waster Isles), sometimes known as the Long Isle/Long Island ( gd, An t-Eilean Fada, links=no), is an island chain off the west coast ...
to
Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...
. The Wicklow Reef in the
Irish Sea The Irish Sea or , gv, Y Keayn Yernagh, sco, Erse Sie, gd, Muir Èireann , Ulster-Scots: ''Airish Sea'', cy, Môr Iwerddon . is an extensive body of water that separates the islands of Ireland and Great Britain. It is linked to the Ce ...
lies at a depth of 12-30 metres (39-98 ft) and is the only known example of a sub-tidal ''Sabellaria alveolata'' reef off the coast of Britain and Ireland.


Habitat and ecology

''Sabellaria alveolata'' occurs on the bottom third or so of the intertidal zone and in the shallow subtidal zone. The worms construct different types of structures depending on the conditions. Where it occurs along rocky shorelines among bladderwrack then the agglomeration of tubes vary from thin encrustations if they are present at low densities to dense hummocks and mounds where there is a high density. The tubes are built from shell fragments or sand and are used to protect the worm from predators and can be repaired if damaged near the entrance. The tube is made up of a number of overlapping layers of material glued together with mucus. There are two sexes and
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 aquat ...
takes place in the spring and again in the autumn. The larvae develop in the water column and can detect the substance the adults use to bind their tubes and follow this to find a location to settle on. They are filter feeders and use cilia covered tentacles to extract food from the water. The reefs that they build encourage biodiversity.


Conservation

''Sabellaria alveolata'' is a UK Biodiversity Action Plan species. Published in 1994, the plan encouraged the mapping and surveying of ''S. alveolata'' reefs. It is also included in local Biodiversity Action Plans e.g.
Newry, Mourne and Down Ulster Scots: ''Newrie, Morne an Doon'' , settlement_type = District , subdivision_type = Sovereign state , subdivision_type1 = Constituent country , subdivision_type2 = , subdivision_type3 = , subdivisi ...
in Northern Ireland. In 2010
Natural England Natural England is a non-departmental public body in the United Kingdom sponsored by the Department for Environment, Food and Rural Affairs. It is responsible for ensuring that England's natural environment, including its land, flora and fauna, ...
published a list of habitats of principal importance (priority habitats) which include ''S. alveolata'' reefs and provides a legal conservation mandate.


References

{{Taxonbar, from=Q1147658 Sabellida Animals described in 1767 Taxa named by Carl Linnaeus