Chalinula loosanoffi (Hartman, 1958a) consists of light greyish brown tubes arising from a common encrusting base, coalescing and anastomosing in varying degrees. Very soft. Shaggy-hispid. Skeleton with a high development of spongin and thin spicules, but quite variable among specimens. Megascleres exclusively thin oxeas, 70-120 by 2-4.5 µm. No microscleres. In the fall, most specimens have a layer of gemmules at the base.
Colour: Light greyish-brown.
Shape, size, surface and consistency: Varying from thinly encrusting to tubular. In the tubular sponges there are several tubes arising from a common encrusting base. They coalesce and anastomose in various degrees and are gradually tapering into small terminal oscules. Tubes up to 2-3 cm high and 5 mm in diameter. Surface slightly to strongly hispid, somewhat shaggy. Consistency extremely soft and compressible.
Spicules: Megascleres only, consisting of oxeas of variable size and form: 70-120 x 2-4.5 µm. Conspicuous is the high number of malformed spicules. Thin centrotylote oxeas are the most common abnormalities, but also short strongyles occur.
Skeleton: No ectosomal skeleton is developed. The choanosomal skeleton is an irregular anisotropic reticulation (chalinula_loosanoffi_sk.jpg) of spongin fibres. The primary fibres are cored by 2-5 spicules, the interconnecting ones by 1-3 spicules. Interconnecting fibres typically two spicules in length (as is usual in the genus). Sometimes spongin is less well-developed.
Reproduction: Larvae were observed in the beginning of October; they are light brown with a darker coloured ring of long cilia (Wapstra and Van Soest, 1987).
Gemmules: This is one of the few marine species with an asexual overwintering stage consisting of gemmule-like structures formed in the autumn at the base of the sponge (chalinula_loosanoffi_ba.jpg). In spring the gemmules hatch to form new sponges. Size of mature gemmules 300-400 µm. Gemmules are protected by a feltwork of oxeas embedded in a spongin envelope (chalinula_loosanoffi_ge.jpg).
Ecology: Intertidal and sublittoral down to 15 m. On shells of mussels and oysters, on wharf piles, undersides of pontoons, etc. Also in brackish and estuarine habitats.
Distribution: New England (U.S.A.) (Hartman, 1958a) and SW Netherlands (Van Soest, 1976; De Weerdt, 1986). Also dubiously reported from Ireland (Van Soest and Weinberg, 1980).
Etymology: Named after Dr Victor Loosanoff, director of the Biological Laboratory of Milford, Connecticut, during the 50's.
Type specimen information: Paratypes BMNH 1965:7:31:4 and 19220.127.116.11 (wet + slide, as Haliclona), Milford Harbour, Connecticut, U.S.A. Holotype in Yale Peabody Museum, Harvard, USA. European vouchers: ZMA POR. no's 3552, 4084, 4100, 4176, 4178, 4192, 4324, 5652, 6003, 6005, 6018, all from SW Netherlands.
Chalinula loosanoffi is clearly distinct from the other European chalinids by its extreme softness and by the presence of gemmules which is unusual for encrusting/tubular chalinids. The conspecifity of the Dutch sponges with the North American species "Haliclona" loosanoffi has been demonstrated by Van Soest (1976).
It is almost certain that the species has been introduced in the Netherlands through the import of oysters. Its occurrence in the estuary of the Schelde is rare, and there are only a few places where the species is regularly found. These populations appear, however, to be stable, which is obviously due to the gemmules.
A common feature in the Dutch sponges is the abundant presence of malformed spicules, usually irregular centrotylote oxea, but also centrotylote styles and strongyles. This was already mentioned by van Soest (1976), but not by Hartman (1958) in his description of the species. In the slide on one of the paratypes, from Milford Harbour, there are only a few styles. Possibly the form of the spicules is influenced by salinity fuctuations, but this needs to be investigated.
The more or less sympatric Chalinula limbata differs from the present species in its much firmer consistency, in the higher development of spongin, and by the absence of gemmulae.
To the south there are three further representatives of the genus. These are Chalinula renieroides Schmidt (1868) (Mediteranean-south-eastern N Atlantic, recently recorded from the Azores by De Weerdt and van Soest (1986, cf. description in this file), Chalinula parasimulans (Lévi, 1959) (West Africa) and Chalinula nigra Boury-Esnault and Lopes, 1985 (Azores).
Sources: Van Soest, 1976; De Weerdt, 1986.