Family CESTIDAE Gegenbaur, 1856

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Introduction

The Cestidae is a family of pelagic ctenophores with two genera, Cestum and Velamen; one species, Cestum veneris, has been recorded from Australian waters. These animals, extremely compressed in the tentacular plane and greatly elongated in the stomodaeal plane, have a ribbon-like appearance. Species of Cestum can exceed 2 m in length in the stomodaeal axis, whereas species of Velamen reach only 15 cm.

The substomodaeal comb rows are elongate, extending along the entire aboral edge. The subtentacular comb rows are greatly reduced. The substomodaeal meridional canals extend along the aboral edge. The subtentacular meridional canals arise under the subtentacular comb rows (Cestum) or equatorially from the interradial canals (Velamen); they extend equatorially to the lateral edges, joining the substomodaeal meridional canals. The paragastric canals extend along the oral edge, fusing with the substomodaeal and subtentacular meridional canals. Gonads are found only along the substomodaeal meridional canals, and are continuous (Cestum) or discontinuous (Velamen). A ciliated oral groove extends along the entire oral edge.

Tentacles and tentacle bulbs are present, but the homologies are unclear. There are either two primary tentacles, with numerous side branches fixed in the oral groove, or reduced primary tentacles, with numerous secondary tentacles along the oral edge. Introduction adapted from Harbison & Madin (1982).

Diagnosis

As for the order.

General References

Harbison, G.R. & Madin, L.P. 1982. Ctenophora. 707-715, pls 68-69 in Parker, S.P. (ed.). Taxonomy and Classification of Living Organisms. New York : McGraw-Hill Vol. 1.

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