Axinella damicornis (Esper, 1794)


Family : Axinellidae

Form: Branching-erect with branches compressed and 'webbed' together. Variable in appearance. Up to 10 cm in height, with short stalk. The fusion of the branches tends to result in irregular growth forms in taller specimens. In lower growing, squatter specimens the lamellae become fused and convoluted, producing growth forms that are not unlike miniature 'ross coral' (Pentapora foliacea). The terminal branches are about 3mm in diameter.

Colour: Bright to deep yellow, verging sometimes towards deep orange at the margins. Distinctively 'bright'.

Smell: None.

Consistency: Firm with strong axial skeleton. Lamellae are flexible.

Surface: Characteristic 'mealy' appearance to the surface, as though dusted with small yellow particles. Surface velvety, with projecting spicules of uneven length, approximately twice that of Axinella dissimilis. Wide canals run up the sponge to arrive radially at 'vents' on the distal edges of the lamellae.

Apertures: Small oscules are borne on the apices of the lamellate branches. When alive, the open oscules are partially surrounded by a small triangular 'flap' of tissue, arising from the oscular rim. On collection this flap cannot be differentiated and the oscules themselves become inconspicuous.

Contraction: Not noticeable.

Internal characters

Skeleton: Plumose. A dense central core composed mostly of bundles of (3 or 4) oxea, forming a plumose reticulation, which terminates in brushes of styles which penetrate the surface.

Spicules: Strong oxea (a), bent to a greater or lesser degree in the middle, occasionally with tylote swelling(s), typically ca. 400-(450)-520Ám. Strong styles to subtylostyles (b), occasionally tylostyles, 420-(630)-1030Ám long, slightly bent.

Habitat: In Lough Hyne - on vertical cliff face at 15m in sheltered location. In Donegal - on rock reefs at 30m. In both localities Axinella dissimilis is also present. Donegal locations are moderately exposed to wave action. Eunicella verrucosa and Alcyonium glomeratum are also characteristic of the habitat. It occurs in similar habitats in SW Britain, sometimes in silty locations, always (?) on sloping rock surfaces (G.A.). Often found partly hidden in hydroid/bryozoan undergrowth on Lundy. In the Mediterranean this is a common species, often covered with the zoanthid anemone Parazoanthus axinellae.

Distribution: Scarce in the British Isles. Known recently from Ireland: Lough Hyne, Co. Cork; Skird Rocks, Galway Bay; St. John's Pt., Co. Donegal; Rathlin O'Birne Is., Co. Donegal; Rathlin Is. and Portrush, Co. Antrim; Ardnoe point, Sound of Jura, W. Scotland; Scilly Isles; Channel Isles; Devon; Lundy; Roscoff; a common Mediterranean species.

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

Identity: The overall form is similar to Stelligera rigida but the mealy appearance of surface and bright yellow colour are characteristic. Most readily confused with Axinella verrucosa (Esper, 1794:275), so far recorded from Roscoff and the Channel Isles (see Table below). It may be synonymous with Axinella pyramidata Stephens 1921:63, but this species has only been recorded from Roscoff since it was first described from off Co. Kerry at 68m. Spicule complement confirms Axinella sp. but all Axinella species have similar spicules with only size and subtle shape differences between species.

Voucher: BELUM : Mc1306. Brittany, France.

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

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