Form: Varies from thinly encrusting patches to smoothly rounded lobes to tall, chimney-like growths with large terminal oscules or laterally spreading masses of anastomosing branches. The shape of this species is highly variable.
Colour: Grey-brown to purple-brown, evenly coloured over all of the sponge. The purple-brown form may be characteristic of better illuminated sites in shallow or clear water. Goes whitish in spirit (?consistently).
Smell: ? Slime : None obvious, but slime strands appear when the sponge is pulled apart.
Consistency: Very soft and flexible - one of the softest Haliclona species.
Surface: The surface layer is not apparently differentiated from the body of the sponge. It is smooth, and on close examination is seen to consist of a loose network of tissue with irregular spaces between the strands, giving a characteristic, 'loosely woven' appearance.
Apertures: The oscules are terminal on raised lobes, or at the ends of tall chimney structures. The oscules are flush with the rounded ends of these chimneys, and do not have a raised membranaceous edge as in many other Haliclona species.
Contraction: Not noticeable.
Skeleton: Ectosomal skeleton is a regular six-angled unispicular reticulation of single spicules bound at the nodes by a variable amount of spongin. Choanosome is a loose network with thin unispicular tracts and a reticulate linking skeleton of single spicules. Spongin reinforces the joins between spicules but may vary considerably in amount. When it is abundant the skeleton may become more irregular.
Spicules: The spicules are short and fat oxea, abruptly pointed, often with strongylote or stylote modifications, 80-130 x 4-8Ám. There are also thin developmental oxea, both incorporated into, and outside of, the reticulate skeleton.
Habitat: Frequent in water 10-30m deep in moderately exposed sites, and also in sites which are sheltered but have moderate tidal streams. The tall chimney-like form only develops in the more sheltered conditions. Also present in very shallow water and under stones in the intertidal.
Distribution: Widespread in Ireland; W. coast of Scotland; English Channel. "Shetland; France; Mediterranean; Azores; West Africa."
Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.
Identity: The slime strands when the sponge is pulled apart appear to be the most consistent and characteristic unique feature of this species. The smoothly rounded appearance of the oscular chimneys, when present, differentiate it from the other species with oscular chimenys, such as Haliclona viscosa, where they are rugose. Spicule size and shape aid separation from Haliclona rosea, which can look similar. Finally the white coloration in alcohol may prove to be a useful character.
Voucher: BELUM : Mc1409. Carna, Galway.
Editors: D. Moss, B.E. Picton.
|Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland |
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