Merten's Carpet Anemone

Mertens' carpet anemone is a reef anemone that hosts 13 to 14 fish species, including 12 to 13 anemonefish. It lives over coral and rocky substrates on reefs.

The fish and the anemone both gain from the arrangement. The stinging tentacles keep the fish safe from predators, while the fish keep water moving through the anemone as they swim, clean away parasites and guard its oral disc.

Colour varies, so look underneath. There are always orange spots on the body, and the tentacles are not sticky, which separates it from Stichodactyla haddoni.

Like other sea anemones, it is a solitary polyp with no skeleton. The basal disc lets anemones creep along and dig into place, although some are nearly impossible to shift once settled. Fringing tentacles come in sixes or multiples of six. Most anemones eat plankton, but they can take anything caught by their stinging tentacles, including quite big fish. Some also live alongside crabs, shrimps and brittle stars.