Order DENDROCERATIDA Minchin, 1900

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Diagnosis

Demospongiae in which a fibre skeleton is always present but, as compared to Dictyoceratida, is reduced in relation to soft tissue volume. The skeleton arises from a continuous spreading basal plate, and adopts either a dendritic or an anastomosing pattern. In anastomosing forms there is never any clear size distinction between primary and secondary elements. The fibres always contain pith and are strongly laminated, usually quite stout, and in some genera cellular (degenerate spongocyte) elements are incorporated in the bark and to a lesser extent in pith. Free fibrous spicules may supplement the main skeleton. The choanocyte chambers are eurypylous. Mesohyl cell population usually includes secretory cells (termed spumous cells), although their occurrence cannot yet be verified for all genera. Matrix volume is low in relation to chamber and canal volume, and the endosomal matrix is only weakly infiltrated by collagen. This, in conjunction with the light fibre skeleton, makes the sponges soft and fragile. The pith in the fibres is markedly disjunct from the bark, and in structure is close to that of the Verongida. It is common to find dark fibre pigmentation contrasting with the matrix pigmentation, the latter always being uniform throughout the sponge. Larvae are large, incubated parenchymellae, with complex structure, differentiated histology and a terminal clump of long cilia. Biochemically, members of this group are characterised by a moderate sterol content in conjunction with the presence of terpenes, which are always diterpenes.

ID Keys

KEY TO FAMILIES

(1) Fibre skeleton completely dendritic, with fibres always arising from a flat basal spongin plate, and fibres with strongly laminated bark surrounding central distinct pith region --------------------------------------------- Darwinellidae
Fibre skeleton is reticulate with perfectly regular to slightly irregular meshes, and fibres are strongly and coarsely laminate with pronounced pith --------------------------------------------------------------- Dictyodendrillidae

Diagnosis References

Bergquist, P.R. & Cook, S.D.C. 2002. Order Dendroceratida Minchin, 1900. 1067 in Hooper, J.N.A. & van Soest, R.W.M. (eds). Systema Porifera: A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 1. [1067]

General References

Bergquist, P.R. 1980. A revision of the supraspecific classification of the orders Dictyoceratida, Dendroceratida and Verongida (Class Demospongiae). New Zealand Journal of Zoology 7: 443-503 figs 1-25 pls

Bergquist, P.R. & Cook, S.D.C. 2002. Order Dendroceratida Minchin, 1900. 1067 in Hooper, J.N.A. & van Soest, R.W.M. (eds). Systema Porifera: A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 1.

Lendenfeld, R. von 1883. Über Coelenteraten der Südsee. Neue Aplysinidae. Zeitschrift für Wissenschaftliche Zoologie 38: 234-313 pls 10-13

Merejkowsky, C. 1878. Preliminary account on sponges of the White Sea. Trudy Imperatorskago Sankt-St Petersburgskago Obshchestva Estestvoispytatelei 9: 249-270 [in Russian]

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