Species Feature: Parasites

My fascination with marine parasites

Once I had several hundred dives in many countries under my belt I started to get a bit bored with common critters.  Thus began my fascination for the strange and gruesome sightings of parasites, which I always actively seek out.  Lembeh, Indonesia has a high density of parasites such as in the mouth of anemonefish, on the sides of shrimp and whip coral gobies, and on cardinalfish like the parasite with huge eyes.  I found a high concentration of isopod parasites outside Havana, Cuba such as on the blackbar soldierfish, red hind, blue tang, and blue chromis.  The painted comber with about eight large isopod parasites was found in Greece and the odd parasites on the peacock flounder’s eye was located in Cocos, Costa Rica.  Finally some Scottish lochs have a high parasite concentration, like the sea lice on the two spotted goby (Gobiusculus flavescens), which are becoming a huge problem for wild fish since they are spreading from the salmon farmed in cages within the lochs.  The swirly or straight trails behind some of the parasites are their eggs, and what has puzzled me for a while is why a particular isopod parasite species appears brown, grey, or striped, depending on fish species and where it is attached.  It seems the striped parasites are only found on fins, while grey specimens are located on white or blue fish.  If anyone knows why this is please let me know!