Form: Stipitate, the stalk bearing a roughly ovoid, sometimes slightly flattened, body, consisting of a network of thin walled anastomosing tubes. Maximum height 3cms, although specimens are frequently less than half this size.
Colour: White, off white.
Smell: None. Slime : None.
Consistency: "Firm to soft"; even tough and resilient.
Surface: In macro view, the sponge surface is even. The surfaces of the individual tubes are smooth.
Apertures: A single oscule (?sometimes more) borne at the apex of the sponge.
Contraction: Not noticeable.
Skeleton: The skeleton consists of triradiates distributed throughout the body, with diactinal spicules occurring at the base of the body, and in the stalk.
Spicules: The triradiates are of two types: (a) with rays of equal length, 80-300Ám; (b) sagittal triradiates with the basal ray (90-600Ám) longer than the two paired rays (60-300Ám). The latter paired rays may exhibit abnormalities. The diactinal spicules (oxea) (c) are 80-300Ám long. The growth point is normally marked by a central irregularity.
Habitat: On vertical, hard surfaces. Often found attached to empty shells in sheltered conditions in sea lochs. Also reported growing on hydroids and bryozoans. "Littoral to 220m". (Note. This small, inconspicuous and delicate species can be quite difficult to spot. More habitat information is required).
Distribution: Around the Atlantic coasts of Europe it is known from Plymouth, Brittany, Ramsgate, Scarborough, Berwick, St. Andrews, and Shetland. Known recently from Salcombe (Devon), Sound of Jura (Hebrides) and Strangford Lough. Also from the Arctic and Mediterranean.
Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.
Identity: The external form ("like a Clathrina coriacea on a stalk") is characteristic.
Editors: D. Moss.
|Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland |
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