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Triactis producta (Family Aliciidae)

Boxer Crab Anemone


Triactis producta has been recorded from right across the Indo-Pacific. From Torres Strait and Great Barrier Reef, Australia, to the Red Sea, Maldives, Singapore, Guam and Hawaii. (WA, NT, QLD)


The Boxer Crab Anemone is so named because it is sometimes found living on the claws of crabs of the genus Lybia. The crabs use the anemones and their powerful stinging cells for defense.

This anemone is small, growing to 15 mm in height and diameter. The column is translucent pale brown with darker spots on its lower part. The capitulum is dark brown with pale translucent vertical lines. The tentacles are translucent, the oral disc is pale brown and the mouth is orange-brown. The peduncles and fosse have an iridescent blue-green sheen. Zooxanthellae are present in the endoderm of the column, disc, peduncles and spherules indicating that a portion of the anemone's nutrition is gained from photosynthesis.

Up to 60 tentacles, that have a very large number of nematocysts in their distal parts, may be present. The tentacles are long and slender with blunt tips; the surface is granular due to the small groups of nematocysts.

Ecology/Way of Life:

The Boxer Crab Anemone lives on shallow reefs, in living and dead scleractinian coral and on the claws of the xanthid crab, Lybia edmondsoni. Species of the host crab have never been found without the anemone attached to its claws, although the anemone is often found living separately from the crab. The crab carries one anemone on each claw and uses them as a defensive weapon and in the capture of prey. In Hawaii, crabs of the genus Lybia have been seen to remove the anemones from the substrate and attach them to their claws.

Interaction with Humans/Threats:

These anemones have been known to cause quite severe stings to humans. There are no known threats to the Boxer Crab Anemone; however, disturbances within its Queensland coastal habitat may affect this species.

Other Comments:

Other common names for this anemone include Crab Anemone and Pom Pom Anemone.

Further Reading:

Fautin, D.G. (2003) Hexacorallians of the World.

Fosså, S.A. & Nilsen, A.J. (1998) The Modern Coral Reef Aquarium. Birgit Schmettkamp Verlag, Bornheim, 479 pp. Karplus, I., Fiedler, G.C. & Ramcharan, P. (1998) The intraspecific fighting behavior of the Hawaiian Boxer Crab, Lybia edmondsoni — fighting with dangerous weapons? Symbiosis 24: 287 – 301.

Larson, R.J. & Cooper, J.W. (1982) Phylum Cnidaria In, Walls, J.G. (ed.) Encyclopedia of Marine Invertebrates. T.F.H. Publications, Neptune, New Jersey, pp. 66 – 133.


Text & map by Carden Wallace & Zoe Richards, Museum of Tropical Queensland.

Photograph by Neville Coleman.

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