Haddon's sea anemone

Scientific name : Stichodactyla haddoni

Large anemone, with oral disc regularly folded at the edge. The rest of the animal is within the sediment. Short tentacles, with rounded tip, tightly packed, sticky. Tentacle colour is green or brown, sometimes variegated. Whitish column with verrucae in the same colour or pinkish, not adhaesive. Diameter up to 80 cm, more commonly 50 cm.
Distinguished from Stichodactyla mertensii mainly for the different environment: sand for S. haddoni, rocks for the former. On sandy environments also Stichodactyla gigantea is found, but typically in shallower waters. The latter has oral disc folds more deep and uniformly spaced, longer tentacles constantly vibrating.

Associated organisms
This is a species bearing zooxanthellae. It has an obligate symbiosis with anemone fishes like, in our area, Amphiprion polymnus and Amphiprion clarkii. It associates occasionally with the three spot dascyllus Dascyllus trimaculatus, with porcelain crabs like Neopethrolisthes maculatus, with commensal shrimps like Periclimenes holthuisi, Periclimenes ornatus, with different species of cardinal fish (family Apogonidae).