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Acrozoanthus australiae (Family Zoanthidae)

Sea Anemone

Distribution

Distribution:

Acrozoanthus australiae has been recorded from the tropical waters of the Great Barrier Reef, Queensland, from Mackay to the Torres Strait, Darwin and Cambridge Gulf. It has also been found in south-west Sulawesi and the Moluccas Islands of Indonesia. (QLD, NT, WA).

Features:

Acrozoanthus australiae is found attached to parchment-like tubes which project from low intertidal muddy shores. They are exposed on half ebb tides. First descriptions by Saville-Kent (1893) suggested that the polyps built up an erect polypary, but this structure in now believed to be the worm-tube of the polychaete Eunice cf. tibiana (Pourtales). The worm-tube is a zigzag shaped outgrowth, up to 45 cm long. At the apex of each step of the tube, discrete polyps of Acrozoanthus australiae and their buds are found thickly grouped. The spaces between clusters are typically coved with algae, hydrozoans or other marine growths.

The adult polyps reach 2.5 cm in diameter when expanded and have a red-brown spotted dull orange/cream oral disc, matching the body. The red-brown spots continue but become much less frequent along the length of each pinkish tentacle. In the contracted to semi expanded state, a brilliant emerald-green ring is visible near the margin of the oral disc.

Ecology/Way of Life:

Acrozoanthus australiae divides by asexual budding, in which small buds arise in a ring near the base of the column. It is inferred that, since the clone on the worm tube consists of regularly spaced colonies, each comprising a single full-grown polyp and its developing buds, buds separate and move away from their parent as they mature. Sexual reproduction probably also occurs, but has not been observed.

Preferred Image

Interaction with Humans/Threats:

Although the zigzag shaped worm-tube, on which Acrozoanthus australiae lives, is often washed up on beaches, little was known about the biology and life history of this spectacular sea anemone until recently. Since its initial description in 1893, there appear to be no published reports of this species, in Australia, until the 1990s. This may be due to the range of this species being largely restricted to the less frequented 'muddy shores' of northern Australia. Therefore, it may not be under threat from human activity.

Further Reading:

Colin, P.L. & Arneson, C. (1995). Tropical Pacific Invertebrates. Coral Reef Press: Beverly Hills 296 pp.

den Hartog, J.C. (1997). The sea anemone fauna of Indonesian coral reefs. pp. 351–370 in Tomascik T., Mah, A.J., Nontji, A. & Moosa, M.K. (eds) The Ecology of the Indonesian Seas, Part I. Periplus Editions: Republic of Singapore Vol. 7

Fautin, D.G. (1997). Hexacoralians of the World. http://hercules.kgs.ku.edu/hexacoral/anemone2/index.cfm

Ryland, J.S., Brasseur, M.M. & Lancaster, J.E. (2004). Use of cnidae in taxonomy: implications from a study of Acrozoanthus australiae (Hexacoralia, Zoanthidae). Journal of Natural History 38: 1193–1223

Ryland, J.S. & Lancaster, J.E. (2003). Revision of methods for separating species of Protopalythoa (Hexacorallia: Zoanthidea) in the tropical West Pacific. Invertebrate Systematics 17: 407–428

Ryland, J.S. (1997). Reproduction in Zoanthidea (Anthozoa: Hexacorallia). Invertebrate Reproduction and Development 1–3: 177–188

Saville-Kent, W. (1893). The Great Barrier Reef of Australia; its products and potentialities. W.H. Allen & Co: Waterloo Place pp. 152–155, Pl. 343

Saville-Kent, W. (1897). The Naturalist in Australia. Chapman & Hall: London 302 pp.

Tischbierek, H. (1930). Zoanthiden auf Wurmröhren. Zoologischer Anzeiger 91: 91–95

Acknowledgments:

Text and map by Wayne Napier, Museum of Tropical Queensland. Photographs by Andrea Crowler and Wayne Napier.

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Images and Multi-media:  
Attached Image  
image/jpeg 10086 bytes Acrozoanthus australiae at mid ebbing tide, with tentacles contracted showing the brilliant green ring.
Distribution Map  
image/jpeg 4325 bytes Distribution of Acrozoanthus australiae
Attached Image  
image/jpeg 14177 bytes Acrozoanthus australiae with tentacle displayed
Attached Image  
image/jpeg 10072 bytes Dried worm-tubes of Eunice cf. tibiana that wash up on beaches.

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