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(Schmidt, 1875)

Species Overview

Coelosphaera (Coelosphaera) physa (Schmidt, 1875) is a small conical bladder-like sponge with a nipple-like pointed end. It has a tough leathery skin and is empty of skeletal material excepting a fragile centre. It is known only from deeper water in the Scandinavian fjord areas and off SW Ireland.

Taxonomic Description

Colour: Not known.
Shape, size, surface and consistency: Conical fistular or bladder-like sponges, with a nipple-like pointed upper end. Size up to 1.5 cm high and 1.1 cm in diameter. Surface smooth, but slightly rough to the touch. Apical nipple provided either with an oscule or with a pore-sieve. Consistency of "skin" leathery. Inside mostly empty of skeletal material and thus the sponge may be flattened when pressed.
Spicules: (Coelosphaera physa 2) Tylotes, isochelae and raphides. Megascleres: Tylotes, long, slender, with elongated tyles, occasionally strongyle-like with barely developed tyles: 500-890 x 12-13 µm. Some authors report also styles, but they may not be proper.
Microscleres: Arcuate isochelae: 35-58 µm; raphides in trichodragmas, size not recorded.
Skeleton: Ectosomal skeleton is a thick feltwork of tangentially arranged tylotes, with intermingled microscleres. Choanosomal skeleton: from a confused central basal mass of tylotes rises an irregular, frail network of thin bundles of tylotes. The latter collapses during preservation.
Ecology: On rocky bottoms below 80 m, down to at least 550 m.
Distribution: Fairly common in the Skagerrak and the Swedish and Norwegian fjords; SW Ireland. Also recorded from the North Pacific and the Azores.
Etymology: physa (Greek) = bubble, referring to the hollow habit.
Type specimen information: A slide of the holotype is preserved in the Berlin Museum, reg.no. ZMB 6570, Bukenfjord, Norway. A presumed type fragment is preserved in the Strassbourg Museum, reg.no. MZUS P0125, from Norway, 1873 (Desqueyroux and Stone, 1992).


A second Western European species of Coelosphaera, C. (C.) tubifex Thomson (1873) differs in having several fistules on top of a globular body, and in possessing sigmas and lacking trichodragmas. That species also occurs in deep water (below 200 m), off the coasts of the Faroes, Ireland and further to the west and the south.
Source: Arnesen, 1903.

Coelosphaera physa