Family SYCETTIDAE Dendy, 1892

Museums

Regional Maps

Introduction

Sycettidae Dendy, 1892 have tubular, spherical, flask-shaped, ovoid and branching growth forms, and occur as solitary sponges or in groups. The ectosomal cortex is continuous and strengthened by tangential spicules, but these do not cover the choanocyte chamber layer. Choanosomal spicules, supporting choanocyte chambers, have an articulated arrangement of overlapping sagittal triradiates (Hooper & Wiedenmayer 1994: figs 149, 155), with the angle between the paired rays larger than the angles between each paired ray and the long, unpaired ray. The sagittal triradiates have the longest ray pointing to the exterior of the sponge, and form a layer beneath the spongocoele lining (referred to as the subgastral position). Pseudosagittal spicules absent. Collar-cells are usually confined to the radial chambers in the adult, and probably always have apical nuclei. Choanocyte chambers are asconoid, tubular, being arranged radially around a central atrium (spongocoele), and the ends of chambers project to a greater or lesser extent on the ectosomal surface.

The family comprises four genera, one of which (Sycodorus) is not well known. Species are widely distributed in the world's oceans. They occur from intertidal waters to depths of at least 3800 m (Hartman, 1982). Two of these genera have published records for the Australian fauna.

Reviews and discussions can be found in Dendy (1893); Minchin (1900; unchanged); Dendy & Row (1913; unchanged); Tanita (1943; keys to Sycetta and Sycon); Hartman (1958; in Sycettida); Burton (1963; dropped); Borojevic (1967); and Hartman (1982).

Diagnosis

Leucosolenida with a central atrial tube and perpendicular regularly arranged radial tubes lined by choanoderm. The distal cones of the radial tubes, which may be decorated with tufts of diactines, are clearly noticeable on the sponge surface. They are never covered by a cortex supported by tangential triactines and/or tetractines. The proximal skeleton of the radial tubes is composed of a row of subatrial triactines and/or tetractines, which are usually followed by only a few or several rows of triactines and/or tetractines. Distal pseudosagittal spicules are absent. A tangential layer of triactines and/or tetractines supports the atrial wall.

ID Keys

See order Leucosolenida diagnosis

Diagnosis References

Borojevic, R., Boury-Esnault, N., Manuel, M. & Vacelet, J. 2002. Order Leucosolenida Hartman, 1958. pp. 1157-1184 in Hooper, J.N.A. & Soest, R.W.M. Van (eds). Systema Porifera. A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 2. [1162]

General References

Borojevic, R. 1967. Eponges calcaires recueillies en Nouvelle-Calédonie par la Mission Singer-Polignac. In, Expéd. Franç. Récifs Coral. Nouv. Caléd Paris : Fond. Singer-Polignac. Vol. 2. 11 pp. 4 figs

Burton, M. 1963. A Revision of the Classification of the Calcareous Sponges. London : British Museum pp. 1-693 figs 1-375.

Dendy, A. 1893. Studies on the comparative anatomy of sponges. V. Observations on the structure and classification of the Calcarea Heterocoela. Quarterly Journal of Microscopical Science 2 35: 159-257 pls 10-14

Dendy, A. & Row, R.W.H. 1913. The classification and phylogeny of the calcareous sponges, with a reference list of all the described species, systematically arranged. Proceedings of the Zoological Society of London 1913: 704-813

Hartman, W.D. 1958. A re-examination of Bidder's classification of the Calcarea. Systematic Zoology 7: 97-110

Hartman, W.D. 1982. Porifera. pp. 640-666 in Parker, S.P. (ed.). Synopsis and Classification of Living Organisms. New York : McGraw-Hill Vol. 1.

Minchin, E.A. 1900. Porifera. pp. 1-178 in Lankester, E.R. (ed.). A Treatise on Zoology. The Porifera and Coelenterata. London : Adam and Charles Black Part 2.

Tanita, S. 1943. Studies on the Calcarea of Japan. Science Reports of the Tôhoku University Biology 17: 353-490 pls 11-18

History of changes