When someone mentions ‘leeches’ your mind invariably imagines a large, thick, dark bloodsucking worm-like creature that are likely to suck onto someone’s skin from a tropical forrest or an Asian swamp. But for some reason marine leeches don’t fit this stereotype at all, being small, colorful, and usually only found – or at least photographed – parasitizing blennies.
Thankfully, we’ve almost never seen marine leeches show up with the wild reef fish that we encounter in the aquarium hobby, but eagle eyed divers do spot them in photographs of some blenny species. We have to believe that blennies are most often targeted because they like to rest inside holes of rock or the reef where they can be easy targets for leeches when they are motionless, but this is just a guess.
But the reason we’re even writing about this darned pest is that the marine forms are so dang colorful! We went way down the blenny hole of marine leeches in a previous article way back in 2013 where the Kamohara blenny was found to be loaded up with this black and white striped ectoparasite.
But some recent images by Ned DeLoach shows a similar blenny species this time infested with its own orange and white striped marine leeches. With so many species of cleaner fish, cleaner shrimp, and even some cleaner hermit crabs, there’s a whole ecological cottage industry in the ocean of ridding marine fish of their parasites. Marine leeches must have found a narrow loophole in blennies to keep from being picked off, and that striped pattern might be some form of visual trickery to throw off any cleaners that might want to pick it from its host. [BlennyWatcher]