About Stichodactyla mertensii Brandt, 1835
Stichodactyla mertensii, commonly called Mertens' carpet sea anemone, is a species of sea anemone belonging to the family Stichodactylidae. It is considered the largest sea anemone, with a diameter exceeding 1 meter (3.3 feet); the next largest species is Heteractis magnifica, which has longer tentacles. The oral disc of this species is more ovoid than circular, and it contours to the surrounding substrate. It attaches to the substrate via adhesive verrucae, which are wart-like projections. Its tentacles are either blunt or pointed, uniformly shaped, and only 1–2 centimeters (0.39–0.79 inches) long. This species hosts obligate symbiotic zooxanthellae, and acts as a host to approximately half of all anemonefish species, plus one species of damselfish, Dascyllus trimaculatus. S. mertensii lives on rocky or coral substrate, and is widespread across tropical and subtropical waters, ranging from Mauritius to Fiji, and from the Ryukyu Islands of southern Japan to Australia; it is also found in Hawaii, USA, North America. This species can be mistaken for Stichodactyla gigantea and S. haddoni, but the three can be most easily distinguished by habitat: S. gigantea and S. haddoni prefer sand, while S. mertensii prefers rocky or coral substrate.
