''Halecium muricatum'', commonly known as the sea hedgehog hydroid, is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specializ ...

n in the family

Haleciidae Haleciidae is a family of hydrozoans. Their hydroid colonies emerge from a creeping hydrorhiza and usually form upright branching colonies, although some species' colonies are stolonal. Their gonophores are typically sporosacs, growing sing ...

. It occurs mainly in arctic and northern temperate waters, in both the Atlantic and Pacific Oceans.

Description

''Halecium muricatum'' is a colonial hydrozoan. It is arborescent, forming stiff bushy colonies usually between in height but sometimes . The main stems are robust and mostly straight, with a few large side branches diverging irregularly, each forming an angle of 30° with the main stem. Finer tertiary branches are formed as the polyps each elongate and bud new polyps on alternate sides of the often single plane branch; there is a clearly defined node between each segment. Gonothecae (reproductive structures) develop on the stem and main branches; both male and female gonathecae are ovate and covered with rows of spines and appear identical. The colony is typically yellowish.

Distribution and habitat

''Halecium muricatum'' is found in the northwestern Atlantic Ocean and the northern Pacific Ocean. It is mainly an arctic and northern temperate species and is present in Greenland and Iceland. In America its range extends southwards to

Cape Hatteras Cape Hatteras is a cape located at a pronounced bend in Hatteras Island, one of the barrier islands of North Carolina. Long stretches of beach, sand dunes, marshes, and maritime forests create a unique environment where wind and waves shap ...

and it is also present in Alaska and in the seas around Siberia. In Europe it extends southwards as far as the British Isles. Here its range extends from the western coast of Scotland southward to West Wales where it occurs around

Lundy Island Lundy is an English island in the Bristol Channel. It was a micronation from 1925–1969. It forms part of the district of Torridge in the county of Devon. About long and wide, Lundy has had a long and turbulent history, frequently changi ...

and

Skomer Island Skomer () or Skomer Island is an island off the coast of Pembrokeshire, in the community of Marloes and St Brides in west Wales. It is well known for its wildlife: around half the world's population of Manx shearwaters nest on the island, the At ...

; it is commonest in Scotland and tends to occur only in exposed locations further south. It chiefly grows in gullies and on vertical rock faces, at depths between .

Ecology

This hydrozoan is predated by the

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to mat ...

Zelentia pustulata ''Zelentia pustulata'' is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusc in the family Trinchesiidae. Distribution This species was described from Cullercoats, North Sea, England. It has been reported from the NE ...

'', which feeds almost exclusively on it, and winds its egg coils around its branches.

References

{{Taxonbar, from=Q2475381 Haleciidae Animals described in 1786