Warty Sea Anemone, Bunodosoma cavernatum

Warty Sea Anemone, Bunodosoma cavernatum. Underwater photograph taken in coastal waters off Cozumel Island, Quintana Roo, March 2021. Photograph and identification courtesy of Marina Sutormina, Stockholm, Sweden.

Phylogeny: The Warty Sea Anemone, Bunodosoma cavernatum (Bosc, 1802), is a member of the Actiniidae Family of True Sea Anemones. The Genus Bunodosoma is one of fifty-seven genera in that family, and there are thirteen species in this genus. This species is one of four Bundosoma found in Mexican waters of the Caribbean. This species is also known as the American Warty Anemone. In Mexico, it is called anémona verrugosa. The Pacific coast of Mexico also has a Warty Anemone, Bunodosoma californica.

Morphology: The Warty Sea Anemone is robust with a muscular trunk that is covered with ninety-six rows of small, rounded, wart-like vesicles. They vary in color from shades of olive-green, orange, red or brown. The tentacles are olive green, pale orange or reddish, with the oral disc being yellowish-brown, reddish-brown or olive green. Some have faint pale radial striping or spots on their oral side. The area around the mouth can be reddish. The oral disc is smooth with ninety-six moderate length conical tentacles arranged in groups of five that are smooth and tapering with the inner tentacles being longer than the outer ones. At the base of the tentacles are forty-eight rounded armed stinging cells known as acrorhagi. They reach a height of 10 cm (3.9 inches), with a 5.0 cm (2.0 inch) disc, and with tentacles extended can reach 40 cm (1.6 inches) in diameter. They are active nocturnally, expanding their tentacles; during daylight hours they contract into a reddish gelatinous blob.

Habitat and Distribution: The Warty Sea Anemone is found on rocks, jetties, other hard substrates, and coral rubble. They live in the lower portions of the intertidal zone and at depths up to 6 m (20 feet). The Warty Sea Anemone is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.

Diet: Warty Sea Anemones are nocturnal predators. They feed on small fish,  invertebrates, and larger zooplankton, which they capture with their ninety-six tentacles. Warty Sea Anemones are also zooxanthellate, meaning that they have a symbiotic relationship with single-cell dinoflagellates, known as zooxanthellae. Zooxanthellae live within certain Coral Polyps, Sea Anemones, Jellyfish, and Nudibranchs. The zooxanthellae produce energy, during daylight, by means of photosynthesis. This energy is passed along to their hosts, sometimes providing up to 90% of the host’s total energy needs.

Predators: The Warty Anemone’s stinging tentacles provide defense from some predators and it can also can roll its tentacles and disc inward forming a stumpy blob that is difficult for predators to attack. Even with these defense mechanisms, Warty Sea Anemones are eaten by fish, starfish, gastropods, and Loggerhead Sea Turtles.

Reproduction: Warty Sea Anemones are gonochoric (male or female for life). They can reproduce asexually, through binary fission, or sexually. In sexual reproduction the sperm and eggs are expelled through the mouth into the sea. The zygote (fertilized egg) develops into a planktonic larva. The larva metamorphizes, forming tentacles, pharynx, and septa, and settles to the bottom to begin benthic life.

Ecosystem Interactions: As zooxanthellate organisms Warty Sea Anemones have a symbiotic relationship with zooxanthellae dinoflagellates. These zooxanthellae provide energy for the anemones and the anemone provides nutrients, carbon dioxide, and a secure, sunlit, platform for the zooxanthellae. Warty Sea Anemones do not form relationships with fish, such as Clownfish or Anemonefish, as other Anemones do in the Indo-Pacific.

Human Interactions: Warty Sea Anemones have no direct impact on human activities. They are not targeted by fisheries or the aquarium trade. 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:  Actinia cavernata, Anthopleura cavernata, Bunodes cavernata, Bunodosma cavernata, Bunodosoma cavernata, Phymactis cavernata, and Urticina cavernata.