(Grant, 1826)
Species Overview
Haliclona cinerea (Grant, 1826) is a very variable species, forming grey-brown or purple-brown encrusting sheets with rounded lobes to tall chimney-like growths with large terminal oscules. It is very soft and when torn has characteristic and diagnostic "slime strands". It occurs intertidally under stones and in shallow sublittoral localities with tidal currents.
Taxonomic Description
Colour: Varying from greyish light-brown to dark-purple, evenly coloured overall.
Shape, size, surface and consistency: Polymorphous, varying from small, thinly encrusting patches (Haliclona cinerea De Wrdt), with a few small oscules flush with the surface, to laterally spreading masses (Haliclona cinerea BandW) or anastomosing branches (Haliclona cinerea fresh). Oscules are irregularly scattered and commonly situated at the top of volcano-or chimney-shaped elevations (Haliclona cinerea pink). They are flush, lacking a raised membranaceous edge found in many Haliclona species. The size ranges from a few centimeters in diameter in the small encrusting forms to 20-25 cm in the larger, branched forms. Surface: smooth; it has a "loosely woven" appearance. Consistency: very soft, compressible and fragile, with slime-strands when torn .
Spicules: Characteristically short, rather thick, abruptly pointed oxeas, often with strongylote or stylote modifications: 80-130 x 4-8 µm.
Skeleton: (Haliclona cinerea skeleton) An extensive description of the seasonal variations in skeletal structure and spicule dimensions is provided by Jones (1987, as H . elegans) . Ectosomal skeleton (Haliclona cinerea SEM ecto): a regular, six-angled, unispicular reticulation of spicules, which are connected by spongin at the nodes.
Choanosomal skeleton (Haliclona cinerea skeldraw ): basically the skeleton consists of a regular, isotropic, unispicular reticulation. Spongin: variable, mostly present in fair amounts.
Reproduction: Larvae are violet-coloured, have a ring of longer cilia and a darker coloured bare posterior pole (Meeuwis, 1939).
Ecology: Under intertidal stones, in the infralittoral, to ca. 50 m. It has a preference for sheltered places but with strong tidal currents.
Distribution: Shetland, British Isles: wide-spread in Ireland, W coast of Scotland, Channel Islands, France, reaching south to the Mediterranean, Azores, Madeira and West Africa (Senegal).
Etymology: Cinereus (Latin) = ash-grey, referring to the colour of preserved specimens.
Type specimen information: Neotype of Spongia cinerea : BMNH 1932.1.5.7 (per Burton, 1934a), Cornwall, Great Britain.
Remarks
Haliclona cinerea is characterized in the living state by the slime-strands, but morphologically the species is difficult to describe. When it is growing as thinly encrusting patches under intertidal stones it may be easily confused with Haliclona rosea , which occurs in the same form in this habitat. It differs from this species by the skeletal architecture (H . rosea has no ectosomal skeleton and a choanosomal skeleton of pauci-to multispicular primary lines). More characteristic is the so-called cancellated growth form; the species exhibits this form when it is growing in cavities between stapled boulders at the inlets of sheltered "loughs", for instance. In these circumstances it is found in its most luxurious form and it is frequently covering the greater part of the stone, partly as a thickly encrusting, laterally spreading mass, partly arising to a cluster of inosculating branches.
The skeletal architecture is variable in so far that the amount of spongin greatly influences the regularity of the skeleton. When the amount of spongin is scarce or moderate the skeleton is a regular, mainly isotropic, unispicular reticulation of oxeas (Haliclona cinerea micr) which are at the nodes connected by spongin. When the spongin is more abundant the skeleton becomes more irregular; in extreme cases the skeleton is built up by spongin fibres, which are cored by spicules of reduced size. The ectosomal skeleton shows a similar variation. These factors have been the main reason why so much confusion has risen over the identity of the species in the past.
The species has been revised by de Weerdt and Stone, 1987. One is referred to that publication for more details on this history. IMPORTANT: Jones (1987) refused to accept the synonymy of Haliclona cinerea and H . elegans ; his specimens are conspecific with what De Weerdt (1986, 1987) (followed here) described as H . cinerea .
Sources: De Weerdt, 1987; B. Picton (in Ackers et al., 1985).