Proliferating Anemone, Epiactis prolifera
Proliferating Anemone, Epiactis prolifera. Collected off the beach in San Diego, California, October 2026. Anemone attached to a blade of Giant Kelp, Macrocystis pyrifera. Collection, identification, and photograph courtesy of Mike Johnson, San Diego, California.
Phylogeny: The Proliferating Anemone, Epiactis prolifera (Verrill, 1869), is a member of the Actiniidae Family of True Sea Anemones. The Epiactis Genus is one of fifty-six genera in the Actiniidae Family, and there are nineteen species in the Epiactis Genus. The name Epiactis comes from the Greek words meaning on or upon a “ray”, “radiating structure”, or, more loosely “anemone”. It roughly translates to “upon an anemone”, and refers to the species in the Epiactis Genus attaching themselves, as juveniles, to the column of their parent’s body. The species name prolifera is New Latin and means “proliferating” or “bearing life”, and again refers to this species continuously carrying around their offspring. It is also known as the Brooding Anemone, though that name may also refer generically to anemones in the Epiactis Genus, or specifically to the Giant Brooding Anemone or Lisbeth’s Brooding Anemone, Epiactis lisbethae, and the Small Green Anemone and in Mexico as Anémona Incubadora and Anémona Prolífica.
Morphology: Proliferating Anemones, like many other anemones, attach to the substrate with a pedal base. From there, a body column projects and is topped by an oral disk. The oral disk is rimmed with 48 to 96 short, conical tentacles, These tentacles encircle the mouth. The column and oral disk vary in color and may be pink, red, brown, green, or greenish-brown. On rare occasion, the column base may be blue. Fine white lines radiate from the mouth and across the oral disk. White lines also run lengthwise at the top and bottom of the column. Some specimens have a bright white spot at the base of each tentacle. Proliferating Anemones reach up to 3.0 cm (1.2 inches) in height, and 5.0 cm (2.0 inches) in diameter.
Habitat and Distribution: Proliferating Anemones are generally found attached to algae, eelgrass and rocks. In some cases they attach to decorator crabs or the shells of hermit crabs. They are able to move fairly freely, often in packs at the bottom of tidepools. Proliferating Anemones sometimes camouflage themselves with debris. They are found from the mid-intertidal zone to subtidal depths at depths up to 18 m (60 feet). They are a temperate to subtropical northeastern Pacific species that have a limited range in Mexican waters of the Pacific Ocean being found north of Punga Baja, Baja California along the northwest coast of the Baja Peninsula.
Diet: Proliferating Anemones are omnivorous, sessile, suspension feeders. They use their stinging tentacles to paralyze prey, which includes detritus, plankton and small shrimp. They then pass the food to their mouth. They are an azooxanthellate species. The eating style of the Proliferating Anemone can help to distinguish it from the similar looking Brooding Anemone such as the Giant Brooding Anemone or Lisbeth’s Brooding Anemone, Epiactis lisbethae. When the Proliferating Anemone has food, all the tentacles fold in toward the mouth. When Epiactis lisbethae has food, only the tentacles in contact with the food fold in.
Predators: Proliferating Anemones possess stinging tentacles thause their stinging tentacles to deter most predators. They are known to be preyed upon by the Grey Sa Slug or Shag-run Nudibranch, the Leather Star, Dermasterias imbricata, and some fishes including the Mosshead Sculpin, Clinocottus globiceps, are also thought to eat them.
Reproduction: Proliferating Anemones are gynodioecious indicative that that the small adults are all females and the larger adults are simultaneous hermaphrodites (having both male and female reproductive organs). They primarily self-fertilize, though cross fertilization can occur. The eggs are fertilized inside female gastrovascular cavity, then are expelled, mixed with mucous, before becoming larvae. The eggs are moved via cilia across the oral disk and enfolded on the column. The eggs hatch and attach to the female who provides protected habitat until the juveniles are three to four months of age (4 mm in diameter) and which time they leave and become independent. Proliferating Anemones reproduce year-round, so juveniles of differing sizes may be found attached to the female.
Ecosystem Interaction: Proliferating Anemones are known to host the ectoparasitic copepod Doridicola sunnivae. They also attach themselves to decorator crabs and hermit crabs where they enter into a mutualistic relationship – the anemone providing protection for the crab and the crab providing mobility to the anemone moving the anemone to new food sources or providing food scraps. Additional commensal, mutualistic or parasiticrelationships have not been formally documented.
Human Interaction: Proliferating Anemones have no direct impact on human activities. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.
Synonyms: Epiactis fertilis