My good colleague Dr. Bruce Carlson just uploaded a very nice short YouTube video about a reef blenny called Exallias brevis. Exallias is fairly special (but by no means unique) not just because it’s quite the looker, but because it is a coral predator. Like many blennies it has a mouth that points down (subterminal) and a row of comb like teeth, but unlike most blennies, which use these for cropping algae, Exallias scrapes them across the coral surface, rasping off any tissue that cannot be withdrawn into the cup of any individual polyp. There’s a really nice freeze frame of this in the video. It seems that grazing scars caused by Exallias may have been misinterpreted by some folks as a form of “multifocal bleaching” and there’s some active work happening right now to determine to what degree multifocal bleaching is a real disease issue and how much is the effects of Exallias. Either way, it’s a fascinating little fish and an interesting case study that not everything is as it seems in the ocean.
