Stichodactyla mertensii is found on lagoon, pinnacle and seaward reefs, usually attached to hard reef rock. Color is fairly consistently brown, although sometimes scattered tentacles are white. It is usually occupied by Amphiprion chrysopterus, although some host a pair of Amphiprion tricinctus instead. When living in this anemone, the A. tricinctus are mostly black in color. The anemones are also often host to the crab Neopetrolisthes maculata.
The Stichodactyla mertensii below lived on a large rock on the southern Kwajalein Atoll pinnacle known as N-buoy. We remember this anemone in this location as long ago as 1968, and it was large even then. Now it is one of the largest we know of at Kwajalein, well over a meter in diameter. For many years, it has been occupied by a pair of now very large, black Amphiprion tricinctus.
Stichodactyla mertensii and S. haddoni sometimes look similar, but habitat is a big difference, with the former living on hard reefs and the latter in sand. Another way to confirm which species you see is to look at the side, or column of the anemone. If it is orange spotted, it is S. mertensii.
During a coral bleaching episode, the coral next to this anemone bleached out white.
Part of the coral along the sides of the colony came back, but the top part most exposed to the sun died and was covered with dark algae.
During a subsequent bleaching episode, the rest of the coralhead died and became covered with algae. The anemone was not affected. We have noticed that Stichodactyla mertensii seems less affected by water temperature reaching 30°C, one of the few anemonefish bearing anemones at Kwajalein that seems resistent to bleaching.
However, S. mertensii is not completely immune to the effects of warmer water. The smaller individual below bleached out in the 2014 bleaching episode.
Created 28 July 2018