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Stylobates loisetteae (Family Actiniidae)

Shell-forming Anemone


Stylobates loisetteae is found in soft-sediment at 300-500 m depth, near Rowley Shoals on the north-western shelf of Western Australia. A second Australian species, shown in the illustration occurs near Flinders Reef off the Queensland Continental Shelf. (WA)


This species belongs to an unusual group of anemones that play host to a hermit crab by forming a replica of a mollusc shell as a house for the crab. The appearance of this species is greatly influenced by the carcinoecium - the shell that is secreted at the base of the anemone. They range in colour from cream to pink and yellow.

The mouth is surrounded by 160 to 200 tentacles. The longest tentacles are up to 20 mm in length and become progressively shorter towards the edge. Longitudinal and radial muscles enable the anemone to retract its tentacles and contract its body size. Only female shell-forming anemones have been recorded so sexes are presumed to be separate.

Ecology/Way of Life:

The anemone secretes a chitonous shell, enabling it to grow to keep pace with the growth of the hermit crab. Hermit crabs usually need to change shells as they grow, but in this case the crab keeps one anemone "shell" for its entire life and grows to a relatively large size of up to 75 mm in length. The anemone probably benefits from the hermit crab's protection and feeding activity.

Interaction with Humans/Threats:

Due to its deepwater habitat this species does not appear to be affected by human activities.

Other Comments:

Roughly translated, Stylobates means 'stilt walker', referring to the relationship between the anemone and hermit crab. Two other species of Stylobates have been described — one from Hawaii and the other from Tanzania. These are associated with two different species of Hermit crab of the genus Parapagurus and it is presumed that the crab associated with Stylobates loisetteae is a third and undescribed species of Parapagurus. A possible second Australian species, from North Queensland, is not yet named.

Further Reading:

Devaney, D., Dunn, D.F. & Roth, B. (1980) Stylobates: A shell-forming Sea Anemone (Coelenterata, Anthozoa, Actiniidae). Pacific Science 34:379 – 388.

Dunn, D.F. & Leberman, M.H. (1983) Chitin in sea anemone shells. Science 221: 157 – 159.

Fautin, D.G. (1987) Stylobates loisetteae, a new species of shell-forming sea anemone (Coelenterata: Actiniidae) from Western Australia. Proceedings of the California Academy of Sciences 45: 1 – 7.

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

Griffith, J.K. & Fromont, J. (1998) A catalogue of recent Cnidaria type specimens in the Western Australian Museum of Natural Science, Perth. Records of the Western Australian Museum 19: 223 – 239.


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

Photograph by Alistair Birtles.

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