Phylum KAMPTOZOA

Single Kamptozoan zooid

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Introduction

After Wasson (2002)
Kamptozoans are tiny, tentaculate suspension feeders that live in all oceans of the world. Clonal aggregations of independent zooids are found on invertebrate hosts, while colonies of interconnected zooids grow on various substrata. Each zooid has the shape of a wine glass: a bowl-shaped calyx is supported by a slender, flexible stalk that attaches basally to the substratum. The calyx is ringed by a horseshoe of ciliated feeding tentacles and contains a U-shaped gut, a small ganglion, a pair of protonephridia and one or two pairs of gonads. The space enclosed by the tentacles forms an atrium, the deepest part of which serves as a brood chamber for developing embryos.

Kamptozoan zooids actively bend and twist. Their characteristic motion is reflected in the phylum's scientific name (Greek: kamptestai =to bend) and its common name, "nodding heads". Another name for the phylum, Entoprocta, is less appropriate because it suggests an affiliation with the Ectoprocta (Bryozoa) and it implies erroneously that the anus is completely enclosed by the tentacular ciliation. Kamptozoans bear only a superficial resemblance to bryozoans, with which they were once grouped. Developmentally, kamptozoans are spiralians, but their phylogenetic relationships to other metazoans remain enigmatic.

About 150 species have been described worldwide but kamptozoan diversity probably exceeds 500 species (Nielsen 1989). While they are widespread and are quite abundant in some microhabitats, most of the world's kamptozoans are poorly characterised or not known at all, because most species are tiny and easily overlooked. Kamptozoans occur in all oceans, from the intertidal zone to several hundred metres depth. A few colonial species live in brackish water, and one in freshwater. Representatives of all three major families (Loxosomatidae, Pedicellinidae, Barentsiidae) have been found in every marine region that has been thoroughly surveyed. The fourth family (Loxokalypodidae) has been found only once, in the north-eastern Pacific.

Wasson (2002) provides a synthesis of current knowledge about Kamptozoa, updating the last general English-language description of the phylum provided by Hyman in 1951.

Currently, 16 species are described from Australian waters, but many more remain to be discovered. The Australian fauna is unusually rich and varied and includes the world's largest kamptozoan species, Pedicellinopsis fruticosa, and also some of the world's smallest kamptozoans, tiny Loxosomella species on bryozoan hosts. However, little is known of Australian kamptozoans, with published reports and museum specimens of this group being very scarce, and with only a few detailed taxonomic investigations.

Acknowledgements

Text originally prepared for ABRS by Dr Kirsten Wasson, and subsequently modified by Dr Wasson for publication in the Proceedings of the Royal Society of South Australia, has been used in the introductory sections of this database.

General References

Harmer, S.F. 1915. The Polyzoa of the Siboga Expedition. Pt. 1. Entoprocta, Ctenostomata and Cyclostomata. Siboga-Expéditie Report 28(A): 1-180

Hyman, L.H. 1951. The pseudocoelomate bilateria — Phylum Entoprocta. pp. 521-554 in Hyman, L.H. The Invertebrates. New York : McGraw-Hill Book Company Vol. 3.

Nielsen, C. 1996. Three new species of Loxosoma (Entoprocta) from Phuket, Thailand with a review of the genus. Zoologica Scripta 25: 61-75

Wasson, K. 2002. A review of the invertebrate phylum Kamptozoa (Entoprocta) and synopsis of kamptozoan diversity in Australia and New Zealand. Transactions of the Royal Society of South Australia 126(1): 1-20

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