Microciona laevis Bowerbank, 1866


Family : Microcionidae

Form: Thinly encrusting sponge with open texture to the surface and obvious excurrent channels.

Colour: Grey, cream.

Consistency: Fragile, thin sheet.

Surface: Surface with granular appearance due to ostia.

Apertures: Oscules are transparent rimmed and inconspicuous.

Contraction: Slight.

Internal characters

Skeleton: Plumose columns of large, almost smooth acanthostyles, echinated by smaller spined acanthostyles, surface bouquets of subtylostyles.

Spicules: Long, almost smooth styles measuring 3501000 μm by 810 μm, with no development of the head (a). Minute spines are visible under the SEM. Acanthostyles (b) are 65240 μm by 48 μm, with a slightly tylote head, entirely spined with small spines. Ectosomal styles (d) are 340750 μm by 23 μm, smooth with a slightly tylote head. Toxas (c) are 5080μm by 0.53 μm, distinctively shaped, with a small central flexion and thickened in the mid portion, similar to those of Ophlitaspongia kildensis Howson & Chambers, 1999. The majority are in the thicker part of the range but there are also some very thin, hair-like, toxas.

Habitat: Mostly recorded from deep water but recently found on the surface of a shipwreck at 30m on Rathlin Island, Northern Ireland.

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

Identity: The external appearance is similar to other thin encrusting Microciona species but most shallow-water species are orange in colour. It is not possible to identify this species without a specimen for spicule examination.

Editors: Claire Goodwin & Bernard Picton

 Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland