(Rathke and Vahl, in Müller, 1806)
Species Overview
Haliclona urceolus (Rathke and Vahl, in Müller, 1806) is a brownish soft, stalked-tubular species occurring in sheltered environments in the deeper sub-littoral. Tubes may be single or in clusters.
Taxonomic Description
Colour: Light greyish-brown.
Shape, size, surface and consistency: Basically the sponge consists of hollow cylindrical or slightly compressed tubes originating from a common flexible stalk. Generally the tubes end terminally in an osculum of varying width, but blind-ended tubes may be present. A few oscules at the sides of the tubes may be also present, but this is not a common feature. There is considerable variation in the number and degree of coalescence of the tubes, and also in the length of the stalk. Young sponges are always of a very simple form, and consist of one (Haliclona urceolus MCS3) or two (Haliclona urceolus V), sometimes partly fused, tubes. Older specimens vary from one large (up to 15 cm) tube to a cluster of fused tubes (Haliclona urceolus 2). The larger and older the sponge, the more limp it becomes (Haliclona urceolus Scotland). The surface of young, undamaged sponges is slightly velvety, smooth and minutely hispid (Haliclona urceolus Ireland). In older specimens the surface is less velvety and becomes more shaggy (Haliclona urceolus MCS2). Consistency very soft.
Spicules: (Haliclona urceolus draw 1) Short-pointed, cigar-shaped oxeas of variable size: 95-140 x 5-9 µm in southern specimens, 140-ca. 280 x 9-19 µm in northern specimens (see also table below).
Skeleton: (Haliclona urceolus skel 1) Ectosomal skeleton absent. The choanosomal skeleton basically is a wide-meshed and open, regular reticulation of unispicular primary and secondary lines, which is reinforced by multispicular tracts (Haliclona urceolus skel 2) (Haliclona urceolus draw 2) in older sponges. In small, young sponges the skeleton is more close-meshed, and the primary lines are paucispicular, especially at the periphery. Spongin somewhat variable, but mostly moderate. It is always clearly present at the nodes of the spicules; towards the interior of the sponges the spongin may become abundant, but it is never forming reinforcing fibres.
Ecology: In the infralittoral, to ca. 1000 m, on sediment covered stones and vertical rock faces. Frequently found in sheltered environments, but also found exposed to tidal currents. Riisgård et al. (1993) measured suspension feeding rates in this species.
Distribution: Iceland, Faroe, British Isles (Ireland: Rathlin Island; Scotland: Skye, Tiree, Easdale, Lough Melfort, Lough Long, Clyde; Lundy), Guernsey, Bretagne, the Netherlands, Denmark, West coast Sweden, Norway; Arctic: South-East and West coast of Greenland, Bear Island, Spitsbergen, Kara Sea.
Etymology: Urceolus (Latin) = small pitcher or urn.
Type specimen information: Whereabouts of holotype not known (not in the Copenhagen Museum according to De Weerdt). No type material in BMNH.
Remarks
The conspecificity of Isodictya clava Bowerbank, Chalina pulcherrima Fristedt, Reniera clavata Levinsen, Chalinula robustior Schmidt, Siphonochalina mollicula Lundbeck andReniera simplex Hansen with Haliclona urceolus is certain, since all the relevant material has been studied. Even though no type-material of H . urceolus has been studied (it is not present in the ZMK), the identity of the species could reliably be established through study of the large collection of specimens in the ZMK identified by Lundbeck.
The identity of Spongia laevigata Montagu, 1818 (Britain), Chalina vega Fristedt, 1887 (Liakov, Siberia), Chalina groenlandica Fristedt, 1887 (east coast Greenland) and Reniera glacialis Hentschel, 1916 (Spitsbergen) has been tentatively established on basis of the descriptions and figures; they conform to H .urceolus but study of the original material is needed to assess their taxonomic status. S . laevigata was described as a tubular sponge of a very delicate structure. Montagu compared the specles with the much "coarser" species oculata and dichotoma . His description reminds strongly of H . urceolus .
C . vega was described as arbuscular and pedicelled, with compressed, frequently anastomosing branches and terminal or often lateral, slightly elevated oscules; the oxeas have short points and are 170 µm long.
C . groenlandica was described as blade-shaped with a few larger (than C . vega) oscules, with an exceedingly soft and fragile consistency, and oxeas of 200 µm. Bccause of the large size of the spicula and the extreme softness the species probably conforms to H .urceolus .
R . glacialis was described as a thick-walled tube, without an ectosomal skeleton; the skeleton of the interior reinforced by spicule tracts and with a unispicular reticulation in between the tracts. The oxeas are connected by abundant spongin at the nodes; they have short points and measure 144-168 by 6-8 µm. The conspecifity of R. glacialis with H . urceolus is very likely.
Alander's (1942) records of Haliclona pulcherrima , and H . montagui definitely conform to H . urceolus . His figures (showing limp, stalked tubes) and descriptions leave no doubt about the identity of his specimens.
H . urceolus is rather variable in its growth form and consistency, but especially in the size of the spicules. These factors make it a difficult species to deal with, but the number of studied specimens is sufficiently large to make remarks on the range of the variation. The size of the oxeas seems to be correlated with geographical latitude, since the northern specimens have longer and thicker spicules than the more southern specimens. A similar phenomenon has been demonstrated by Hartman (1958) in American populations of Haliclona oculata . Hartman found larger oxeas in populations north of Cape Cod than in those south of Cape Cod. Whether this variation in spicule size is directly correlated with the water temperature or indirectly by differences in silica content is still under investigation (cf. Simpson, 1978 and Hartman, 1981). Less variable characters of H . urceolus are the terminally situated oscules, the colour which is always greyish-light brown, the architecture of the skeleton and the form of the spicules. A slight variation in the skeletal architecture is that in young, small specimens the skeleton is less wider meshed than in older specimens and that it tends to be paucispicular instead of unispicular and isotropic. The longitudinal reinforcing tracts are absent in young specimens. Thus, the older the sponge becomes, the looser its skeleton and the more it is reinforced by multispicular tracts. These tracts are, however, not very strong, since large specimens collapse immediately when they are taken out of the water. A slight variation was also observed in the form of the oxeas. In young specimens they are slightly more cigar-shaped than in older sponges. They are, however always very sharply and shortly pointed.
In habit H . urceolus is quite similar to Haliclona implexa (Schmidt, 1868), a stalked Mediterranean-Atlantic species. Young specimens may be confused with the sympatric also stalked species Haliclona oculata (Pallas). Furthermore the species must be compared with another stalked chalinid, viz. the Mediterranean species Reniera (= Haliclona) rhizophora Vacelet, 1969.
H . implexa is not included in the present file, but material of this species which was collected by the CANCAP-expeditions of the Rijksmuseum van Natuurlijke Historie, Leiden (NNM) at the Canary Islands, Madeira and the Azores, has been described by de Weerdt and van Soest (1986). Morphologically the species differ only slightly; the stalk of H . urceolus is more strongly developed and longer than in H . implexa , but both species are tubiform, and consist of coalescent tubes with terminally placed oscules. The main and distinguishing difference is the skeletal architecture and the size of the oxeas: H . implexa has a tangential ectosomal skeleton, which consists of a rather irregular, unispicular reticulation of oxeas which are at the nodes connected by a little amount of spongin. The choanosome is irregularly paucispicular, with ill-defined primary and secondary lines. The oxeas are very slender and fusiform and measure only 110 by 2-6 µm. Geographically the two species are well separated.
H . urceolus differs morphologically from H . oculata by its terminally placed oscules, but especially by its hollow tubes. In H . oculata the oscules are normally not terminal. The branches usually end blind and they are not hollow. Full grown specimens are easily separable, but when the sponges are very small and somewhat damaged they might be confused. The skeletal architecture may be very similar in extreme cases, and the same holds true for the size and shape of the oxeas. Generally the skeleton of H . oculata is more rigid, heavily reinforced by spongin, and not by tracts as in H . urceolus . The oxeas of H . oculata are always characteristically cigar-shaped and although they vary in size as well they never reach the size of H . urceolus . Geographically the species overlap largely.
H . urceolus differs from Haliclona (Reniera) rhizophora especially in its skeletal architecture. Through the courtesy of Dr. J. Vacelet (Marseille) the type specimen could be studied; it has an ectosomal skeleton, like H . implexa , but is denser and more confused. The choanosomal skeleton is also more confused. The oxeas are very slender and long: 220-330 x 5-7.5 µm (Vacelet, 1969: 213). H . rhizophora is only known from the Mediterranean. Griessinger (1971) erected the genus Rhizoniera for the species, on the basis of the "rooted" stalk. This character is not considered to be a unique evolutionary development, and thus there seems to be no objective argument to erect a new genus for this single species. Reniera rhizophora is here transferred to Haliclona . Boury-Esnault et al. (1994) described a second species in the genus Rhizoniera , viz. R . pedunculata possessing sigmas and long oxeas (286-410 by 5-8 µm). It was obtained from deep water (>1000 m) on the Atlantic side of Gibraltar.
Table of spicule sizes (in µm) of Haliclona urceolus : Spicule sizes H. urceolus.
Description of individual specimens:
The ZMK specimen from Skagestrand(Iceland), identified as Reniera urceolus by Lundbeck is a very nice specimen, consisting of a single, hollow tube, 10 cm long and of uniform thickness from the base to the top viz. 3 cm; the tube ends in a wide, circular osculum of 6 mm; it originates from a short stalk which is attached to a small stone. The sponge is velvety to the touch and hispid. The consistency is soft, but not limp. The skeleton is a loose-widely meshed, isotropic, unispicular reticulation, reinforced by longitudinal multispicular tracts. The oxea are connected by spongin at the nodes. They have short and sharp points and measure 227 x 14.2 µm (see also table IV in which the spicule sizes of a selection of specimens is given).
The holotype of Reniera simplex is also one single, but very small, hollow tube, 2.5 cm high, very slender at the base but gradually increasing in diameter to 0.5 cm at the top. At the end the sponge is damaged and no osculum can be observed. The stalk is 2 cm. The specimen is strongly hispid, very limp and shaggy. The skeleton is a somewhat confused, isotropic, unispicular reticulation, reinforced by multispicular tracts. There is scarce spongin at the nodes of the spicules. These are very slightly curved, with short points; they measure 233x9 µm.
The lectotype of Isodictya clava is miniscule, but still recognizable as the figured specimen (Bowerbank, 1874, pl. LIII fig. 7). It measures only a few millimeters, and there is no stalk. In BMNH 1877.5.21.2039 a minute stalk of less than a millimeter is present. All the specimens of Isodictya clava are very small, hispid and extremely fragile. The skeleton of the lectotype consists partly of uni-paucispicular primary lines, regularly connected by unispicular secondaries; in other parts is it isotropic. There is a little spongin at the nodes of the spicules. The oxeas are somewhat cigar-shaped, straight and rather small, viz 119 x 5 µm. The three specimens found in the Netherlands, and ZMA. POR. 5655 (Ireland) are very similar to I . clava , both with respect to their small size and to their skeletal architecture. On the average the spicule size of the Dutch specimens is 107 x 6 µm.
The holotype of Siphonochalina mollicula consists of a couple of partly fused tubes, all of them ca. 4 cm high, originating from one stalk. The tubes end terminally in an osculum of 2-3 mm. The specimen is very soft and limp. The skeleton is a very loose and open structure, isotropic and unispicular, and there are no reinforcing fibres The oxeas are cigar-shaped, straight and measure 149 x 8.8 µm.
The holotype of Reniera clavata is very similar to the preceding one, and also very soft, hispid and limp. The skeleton is somewhat more confused, but still clearly isotropic and very loose; there are no reinforcing fibres. The oxeas are connected by a little spongin at the nodes, they are straight and have short, sharp points; they are much longer and thicker than those of the holotype of S . mollicula , viz 228 x 13.7 µm.
ZMA POR. 5559 is a very nice, delicate specimen, consisting of two hollow tubes which are fused at the base and which rise from a stalk of 5 cm. The height of the tubes is 5.5 cm, their diameter O.5 cm. Both tubes end terminally in an osculum of 3 mm. The area below the apices is slightly swollen. One of the tubes has also one osculum along the side. The sponge is very velvety to the touch. The skeleton is isotropic in the centre and paucispicular towards the periphery. The amount of spongin is rather abundant in the centre, nodal at the periphery. The oxeas are cigar-shaped and measure 126 x 6.5 µm.
Source: De Weerdt, 1986