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Updated: Jun 13, 2026

Genotyping of Sea Anemone during Early Development
Published on: May 13, 2019
Evolution of sea anemones (Cnidaria: Actiniaria: Hormathiidae) symbiotic with hermit crabs
Luciana C Gusmão1, Marymegan Daly
1The Ohio State University, Department of Evolution, Ecology and Organismal Biology, 1315 Kinnear Road, Columbus, OH 43212, USA. gusmao.1@osu.edu
Abstract:
Sea anemones in genera Adamsia, Calliactis and Paracalliactis (family Hormathiidae) engage in a mutualistic symbiosis with hermit crabs in which the anemone gains substrate and food in exchange for defending the crab. Some of the sea anemones also expand the living space of the crab by producing a carcinoecium, a chitinous structure that overlies the initial gastropod shell in which the hermit crab lives. The symbiosis is initiated either by the crab, or by the anemone. Although behavioral and physiological aspects of this symbiosis have been studied, interpretations cannot be generalized without an evolutionary framework. After reconstructing relationships among members of Hormathiidae using DNA sequences, we find that the association has evolved at least twice: Adamsia nests within Calliactis in a single clade, and Paracalliactis belongs to a different clade within the family. The carcinoecium and complex behavioral and anatomical features associated with the symbiosis are interpreted as having evolved at least twice within Hormathiidae and seem to be phylogenetically labile.
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