Common names: Hermit Anemone, more...
Synonyms: Actinia bicolor Lesueur, 1817
Species Description: The tricolor anemone, Calliactis tricolor, is a colorful anemone with tricolored pigmentation around the mouth and oral disk, produced by alternating bands of bright yellow, red and pinkish-purple (Ruppert & Fox 1988). The column is generally dull brown, sometimes pink, with cream streaks. Each anemone possesses up to 200 short tentacles that can be white, pink or orange. Two circular rows of pores near the base of the column allow stinging threads, called acontia, to be expelled from the coelenterons when the animal is disturbed.
Habitat & Regional Occurrence: The tricolor anemone is a common species in warm temperate and tropical waters of the Eastern U.S., Gulf of Mexico and Caribbean Sea (e.g. Ruppert & Fox 1988). Although C. tricolor is most commonly known for growing on the shells of hermit crabs and snails, the anemone can become dislodged from its host or intentionally move from location to location, washing ashore or attaching to shell rubble or other hard surfaces (Ruppert & Fox 1988).
Reproduction: The reproductive strategies of C. tricolor are poorly documented. However, Brooks & Mariscal (1985) found that the anemones reproduced asexually via longitudinal fission of the column. While the presence of small anemones in the study area suggested sexual reproduction as well, no spawning or settlement behavior was observed.
Associated Species: The tricolor anemone has well-documented associations with several species of hermit crabs, including: the stareye hermit, Dardanus venosus; the flat-clawed hermit, Pagurus pollicaris; the giant red hermit, Petrochirus diogenes; and the striped hermit, Clibanarius vittatus (e.g.,Bach & Herrnkind 1980, Ruppert & Fox 1988, Brooks 1991). C. tricolor is also known to attach to the carapace of the calico box crab, Hepatus epheliticus (Ruppert & Fox 1988). The presence of the anemones likely protects the crabs from cephalapod predators such as the octopus, Octopus joubini (Brooks 1991). This hypothesis is supported by the higher incidence of both crab-anemone associations and of crabs transferring anemones to their shells in areas where cephalapods and other predators are abundant (Ross 1971, Bach & Herrnkind 1980, Brooks & Mariscal 1986). In turn, the anemones are thought to benefit from the association by sharing scraps of food drifting from the crab as it eats, and by gaining a mobile surface free of competition with other sessile invertebrates (Ruppert & Fox 1988).
Bach CE & WF Herrnkind. 1980. Effects of predation pressure on the mutualistic interaction between the hermit crab, Pagurus pollicaris Say, 1817, and the sea anemone, Calliactis tricolor (Lesueur, 1817). Crustaceana 38: 104-108.
Brooks WR. 1991. Chemical recognition by hermit crabs of their symbiotic sea anemones and a predatory octopus. Hydrobiologia 216/217: 291-295.
Brooks WR & RN Mariscal. 1985. Asexual reproduction by the symbiotic sea anemone Calliactis tricolor (Lesueur). Bull. Mar. Sci. 36: 432-435.
Brooks WR & RN Mariscal. 1986. Population variation and behavioral changes in two pagurids in association with the sea anemone Calliactis tricolor (Lesueur). J. Exp. Mar. Biol. Ecol. 103: 275-289.
Kaplan EH. 1988. A field guide to southeastern and Caribbean seashores: Cape Hatteras to the Gulf Coast, Florida, and the Caribbean. Houghton Mifflin Co. Boston, MA. USA. 425 pp.
Ross DM. 1971. Protection of hermit crabs (Dardanus spp.) from octopus by commensal sea anemones (Calliactis spp.). Nature, Lond. 230: 401-402.
Ruppert E & R Fox. 1988. Seashore animals of the Southeast: a guide to common shallow-water invertebrates of the southeastern Atlantic Coast. University of SC Press. Columbia, SC. 429 pp.
Acrorhagi: Plural of Acrorhagus.
Acrorhagus: Cnidocyte-covered elevation on specialized sweeper tentacles or on the column of anthozoans.
Cnida: An eversible cnidarian organelle that occurs in the cnidocyte.
Cnidae: Plural of cnida.
Cnidocil: A short, stiff, bristle-like cilium that is borne on the cnidocyte and acts as a trigger for the cnida or nematocysts.
Coelenteron: The body cavity and gut of cnidarians and ctenophores; gastrovascular cavity.
Column: The stalk portion of sea anemones.
Hydromedusa: Hydrozoan medusa.
Hydromedusae: Plural of hydromedusa.
Hydrorhiza: Horizontal rootlike stolon of a hydroid colony that grows over the substratum.
Hydrorhizae: Plural of hydrorhiza.
Mesoglea: Connective tissue layer between the epidermis and gastrodermis of cnidarians and ctenophores.
Nematocyst: Stinging cnida of cnidarians.
Ocelli: Plural of ocellus.
Ocellus: A small cluster of photoreceptors; a simple eye.
Oral Disk: Area around the mouth of an anthozoan polyp which bears eight to several hundred hollow tentacles.
Pedal Disk: In some sea anemones, a flattened disc at the aboral end of the column for attachment.
Planula: A cnidarian larva that is elongated and radially symmetrical but with anterior and posterior ends.
Planulae: Plural of planula.
Septa: Plural of septum.
Septum: A double-walled tissue partition in the radial plane of a cnidarian.
Spirocyst: Cnida with a long adhesive thread that functions in capture of prey and in attachment to a substratum.
Tentacle: Evagination of the body wall surrounding the mouth which aids in the capture and ingestion of food.
Zooxanthella: A golden-brown alga, usually a dinoflagellate, that is symbiotic with various marine animals, especially cnidarians.
Zooxanthellae: Plural of zooxanthella.