(Bowerbank, 1866)
Species Overview
Oceanapia robusta (Bowerbank, 1866) is a yellowish-white globular to turnip-shaped sponge with prominent thick-walled fistules protruding from the body. The texture is coarse and hard; the fistules break off rather easily. It occurs in deep waters in the North Atlantic Ocean and Norwegian waters.
Taxonomic Description
Colour: Dirty white alive and in alcohol.
Shape, size, surface and consistency: (Oceanapia robusta Bow) (Oceanapia robusta tubulosa) The sponge consists of a globular body with a diameter of 5-20 cm, with numerous thick, blind fistules, generally arising from the upper parts of the body and the sides. Diameter of fistules 0.5-ca. 3 cm. On the underside of the body a firm root-like structure is present, which is buried in the substrate when in situ. The interior of the body in preserved specimens is filled with a loose and pulpy material which turns dark yellow when dried. The oscules are circular, slightly elevated and measure 2-3 mm. The exterior part of the body is hard and firm, the interior part is fragile and easily broken. The surface is even, slightly hispid from projecting spicules.
Spicules: Megascleres straight or slightly bent robust oxeas, with a sharp, often mucronated point, 170-220-260 by 6-8.5-10 µm. Microscleres thin irregularly curved sigmas, sometimes angulated, 9.5-12.5-17 µm.
Skeleton: (Oceanapia robusta draw) (Oceanapia robusta sk ph) Ectosomal skeleton is a compact multilayered crust consisting of closely packed, mainly tangentially orientated spicules (see drawing), with loosely scattered vertical spicules. The ectosome is supported by a system of branching and anastomosing subdermal multispicular fibres. Choanosomal skeleton in the interior of the body consists of an irregular network of multispicular fibres of variable thickness, with many confused single spicules lying inbetween the fibres. In the fistules, thick multispicular fibres run longitudinally, and sometimes anastomosing, with a loose subisotropic reticulation of single spicules lying inbetween the fibres. Spongin is sparse and nodal.
Ecology: In deeper water, on sandy bottom, 80-1700 m.
Distribution: E-Greenland, Iceland, Faroes, Shetlands, Norway, Ireland; Azores.
Etymology: The name refers to the coarse body and thick-walled fistules.
Type specimen information: ?BMNH 1877:5:2:156, Shetland (not indicated).
Remarks
De Weerdt (1985) studied "original" Bowerbank material, but did not find any specimens matching Bowerbank's descriptions and figures; thus the type status is uncertain. She also studied specimens of Lundbeck, Hansen, Arnesen and Topsent, concluding that all these belong to the same widespread North Atlantic deep-water species, which occurs below 80 m.
Source: De Weerdt, 1985