Hancock, 1849
Species Overview
Cliona vastifica Hancock, 1849 is a red or orange-yellow excavating sponge, boring in mollusc shells. It may be recognized on its colour (light yellow in C . lobata ) and small papillae (similar to C . lobata but much smaller than in C . celata ), and microscopically on its unique possession of spined oxeas in addition to the usual tylostyles and spirasters. It occurs along most coasts of Western Europe from shallow-water down to 600 m.
Taxonomic Description
Colour: Red or orange-yellow.
Shape, size, surface and consistency: Excavating mollusc shells and other calcareous objects. Papillae numerous, but quite small; often arranged in rows. Height about 0.5 mm. Inhalant papillae 0.2-0.4 mm in diameter, exhalant papillae 0.6-1.4 mm. Isolated shells may have up to 600 papillae depending on the species and size of the host; a single shell is normally occupied by a single sponge individual. Galleries (Cliona vastifica galleries) are thin, lobate (lobes up to 3 mm in diameter) and anastomosing to form complicated networks. Consistency soft.
Spicules: Tylostyles, acanthoxeas and spirasters. Megascleres : Tylostyles with rounded head, straight shaft ending very gradually in a sharp point, 145-300 x 4-5 µm. Microscleres : Acanthoxeas, roughened or finely spined over their entire length, fusiform with curved tips, often centrotylote, quite variable in length, 60-160 x 2-7 µm. Spirasters, thin and small with feebly developed spines, undulated or almost straight, variable in length 6-23 x 1-4 µm.
Skeleton: In the papillae the tylostyles are arranged in vertical columns and end in an ectosomal palissade. Interiorly, the spicules are in confusion. Acanthoxeas and spirasters numerous.
Reproduction: Eggs are produced in late September. Asexual "gemmules" are found in the interior of the sponge most of the year.
Ecology: In shells of bivalves, gastropods and barnacles, in corals, from the intertidal down to 600 m.
Distribution: Scotland, Orkney, England, Ireland, Norway, Sweden, Denmark, Germany, France, N Spain; Western Mediterranean. Reported from other parts of the world ocean, but these very probably concern closely related, but different species.
Etymology: Vastificus (Latin) = making empty, making waste, referring to its excavating habit.
Type specimen information: 4 slides in the Hancock Museum, Newcastle-upon-Tyne, reg.no's 4.16.36-39, from Prestonpans, Scotland (Rützler and Stone, 1986).
Remarks
The colour and the tiny papillae enable recognition on sight. For definite discrimination from C . lobata microscopic examination is necessary (presence of acanthoxeas is diagnostic).
The species is less destructive than C . celata , but may still inflict considerable damage to commercially exploited bivalve species. Recent research on the occurrence of C . vastifica in a population of Chlamys islandica has demonstrated that infestation in living shells may come close to 100 %, with noticeable effect on the growth rate of the host (Barthel et al., 1994).
Source: Topsent, 1888a.