''Sabellaria alveolata'', (also known as the honeycomb worm), is a reef-forming

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

. 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 east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

, and from the north

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

to south

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

. It is also found in the

British Isles The British Isles are an archipelago in the Atlantic Ocean, 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 Hebrides, Inner and Outer Hebr ...

at its northern limit in the northeast Atlantic. Its common name is derived from the

honeycomb A honeycomb is a mass of Triangular prismatic honeycomb#Hexagonal prismatic honeycomb, hexagonal prismatic cells built from beeswax by honey bees in their beehive, nests to contain their brood (eggs, larvae, and pupae) and stores of honey and pol ...

-like pattern it creates when building its tube reefs.

Description

''Sabellaria alveolata'' is an

annelid The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to vario ...

(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 component, abiotic (non-living) processes such as deposition (geol ...

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 (: thoraces or thoraxes) or chest is a part of the anatomy of 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 di ...

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 ( , or ), sometimes known as the Long Isle or Long Island (), is an island chain off the west coast of mainland Scotland. It is the longest archipelago in the British Isles. The islands form part ...

Cornwall Cornwall (; or ) is a Ceremonial counties of England, ceremonial county in South West England. It is also one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, ...

. The Wicklow Reef in the

Irish Sea The Irish Sea is a body of water that separates the islands of Ireland and Great Britain. It is linked to the Celtic Sea in the south by St George's Channel and to the Inner Seas off the West Coast of Scotland in the north by the North Ch ...

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 Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

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 Newry, Mourne and Down () is a Local government in Northern Ireland, local government district in Northern Ireland that was created on 1 April 2015 by merging Newry and Mourne District and Down (district), Down District. It covers most of the so ...

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

{{Authority control Sabellida Animals described in 1767 Taxa named by Carl Linnaeus