The mimic anemone, Phyllodiscus semoni, is the ultimate master of deception on the reef. Not only is this anemone a near-perfect copy of various soft corals, stony corals, and even algae, these anemones will mimic a specific type of coral, down to the species!
The mimic anemone has been documented passing for purple acropora, birdnest coral, pink catspaw Stylophora, thick branched Pocillopora, Sarcophyton and Sinularia soft corals, turf algae and there’s even records of P. semoni resembling pipe organ coral. We’ve personally seen P. semoni mimic blue Acropora digitifera, a huge toadstool leather coral, and now we can add one more coral to the mimic anemone’s sneaky wardrobe: pink boulder Porites.
This near perfect clone of Porites lutea was spotted at a reef on the north side of Bali Indonesia, in 15 feet of water surrounded by colonies of the coral it is imitating. In retrospect, it is no surprise that mimic anemones have adapted to resemble pink/purple boulder Porites, as this species is quite abundant on reefs from Mauritius to the Marshall Islands. It’s just a surprise that this is the first we’ve learned of it.
The other astonishing part of this mimic anemone sighting is how large this anemone was, and that what we saw was not even the fully opened anemone and tentacles. The ‘costume’ that mimic anemones wear is actually a modification of its finely branched pseudotentacles which cloak the real body of this anemone during the day.
it’s only at night that the real tentacles and body of the mimic anemone is revealed. When fully opened up some P. semoni anemones can stretch much taller than they are wide; so would this 12 inch wide mimic anemone extend its body up to nearly four feet high?
The truth is, we don’t really know, as we haven’t had the pleasure of coming face to face with this exquisite reef animal on a night dive – which is all the better lest we accidentally came in contact with its necrosis-inducing super stinging tentacles.
It’s always fun to be diving on a natural coral reef and start doing a double take at a wild creature that engenders deja-vu like the mimic anemone. We are already looking forward to seeing what other corals we’ll see P. semoni mimicking next, personally we’re rooting a boulder Porites decorated with Christmas Tree worms.