Haliclona rava (Stephens, 1912)


Family : Chalinidae

Form: Thin sheets, up to 4cm (maybe more) across.

Colour: Greyish yellow.

Consistency: Soft, somewhat fragile, but not friable.

Surface: Even, smooth (? may sometimes be slightly granular?)

Apertures: Oscules more or less level with the surface; small. Osculiferous processes may sometimes occur.

Contraction: Not noticeable.

Internal characters

Skeleton: Irregularly disposed oxea constitute a confused tangential reticulation in the ectosome. The choanosomal skeleton is somewhat confused, with irregular primary lines consisting of a few spicules, and unispicular secondary lines. There are also many randomly scattered single spicules.

Spicules: The megascleres are slender oxea with long, sharp points, ca. 130-260 x 5-11μm. The microscleres are irregularly bent, very small, sigmata, usually ca. 8 x 0.5μm (although a wider range of lengths may be present) and very slender toxa, the latter with a gently curved central flexion and slightly curved apices, ca. 40-120 x 0.5μm. Microscleres may sometimes be scarce.

Habitat: Possibly confined to the intertidal zone, under boulders.

Distribution: Recently known from Ireland and Anglesey, Wales.

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

Identity: The small size, encrusting habit and renieroid skeleton together with the presence of both sigmata and toxa, separate this species from other British haplosclerids, with the exception of Haliclona angulata. (Note, however, that the microscleres may be scarce and difficult to detect). Haliclona angulata is more massive, translucent grey, "purplish and friable", with larger oxea (ca. 200-350 x 3-14μm), and the toxa are characteristically strongly curved and shorter (ca. 40-75 x 0.2-2.5μm).

Editors: D. Moss, B.E. Picton.

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