Coelosphaera (Coelosphaera) appendiculata (Carter, 1874b) is a globular, bladder-like sponge provided with more or less numerous, tubular fistules; free-living, not attached. Surface smooth. The body is surrounded by a solid, bladder-like dermal layer. Oscules in the apex of some of the fistules, pores in the apex of others. Up to 20 mm in diameter. An Arctic deep-water species.
Colour: Yellowish white in alcohol.
Shape, size, surface and consistency: The sponge consists of a globular or tuberous body, from which a few shorter or longer tubular fistules arise. The body may be nearly quite globular, but generally it is of a more or less irregular shape, often somewhat flattened. The fistules are easily broken off; they are cylindrical. The sponge grows freely, without attachment. The body has in the largest specimens a diameter of 20 mm and in the smallest of 8 mm; the length of the undamaged fistule is about 25 mm, the thickness is 2 to 4 mm. The surface is smooth. The oscula are situated at the end of some of the fistules. Other fistules terminate with a slightly swollen knob in which the pores are situated (c_tubifex_papilla.jpg). The consistency is hard and firm, but the inside is soft.
Spicules: (coelosphaera_tubifex2.jpg) Megascleres: These are only of one form, tylotes, more or less curved, the shaft is thickest at the middle: 270-950 x 5-21 µm. Microscleres: Arcuate chelae and sigmata. The chelae have an evenly curved shaft and lobe-shaped alae: 40-46 µm; sigmata: 47-93 µm.
Skeleton: The ectosomal skeleton: the outer rind is highly provided with spicules lying very closely and in several layers, parallel to the surface; the spicules are not scattered, but arranged somewhat circularly round the bases of the fistules; some fine fibres, consisting of few spicules, run lengthwise out through the fistules, lying on the inside of the wall, and continue from the base to the end of the fistules in longitudinal direction. The choanosomal skeleton: some fine fibres are found, but they have no regular course and form no reticulation; they seem mainly to run in directions parallel to the surface. Transverse fibres are not found, and thus there is no reticulation formed. The fibres are somewhat loose, they have an average thickness of 50 µm, and the distance between them is generally 150-250 µm. Spongin is not observed, neither in the inner skeleton nor in the ectosomal skeleton.
Reproduction: Embryo globular and rather large, 300 µm in diameter, lying in a cavity distinctly surrounded by a membrane. It is richly provided with spicules, both megascleres and microscleres.
Ecology: At greater depths, 200-1500 m.
Distribution: W coast of Ireland; Arctic, localities: 60°37'N 27°52'W; 64°45'N 29°06'W; 61°15'N 09°35'W, these localities are situated on the eastern slope of the Reykjanes Ridge, in the Denmark Strait and West of the Faroe Islands.
Etymology: The name refers to the fistular appendages.
Type specimen information: A neotype is in the Natural History Museum, London; BMNH 18220.127.116.11 – labeled ‘Histoderma appendiculata Carter Porcupine stat. 24, North Atlantic, one of Carter’s syntypes’. Paratype: BMNH 1882: 7:28:38 – North Atlantic, ‘Porcupine’ stn. 2 (syntype of Histoderma appendiculata).
The sympatric Coelosphaera (Coelosphaera) physa (Schmidt, 1875) is easily distinguished from this species, as it has no fistules and the microscleres include trichodragmas; sigmas are lacking in that species. Both are deep water species.
Source: Lundbeck, 1910.