The Tongue Parasite “Cymothoa exigua” is a parasitic Isopod and part of the Crustaceans. And it is very commonly seen in Lembeh Strait – probably the best place in the world to study them. Specially in Anemonefish they are very common in the Lembeh Strait – almost every Anemone hosts a fish with that Parasite in its mouth.
The Parasite is first born as a freeswimming male and then finally settles in the mouth of a fish, where it transformes into a female – holding on to the fishes tongue and feeding on the hosts blood from the tongue arterie. The tongue then slowly dies and the Parasite replaces the tongue. But it still functions as a tongue and helps the fish feeding. It now takes a share from the food of the host instead of sucking its blood – so the host does NOT die. At least not, as long as the Parasite remains in the mouth and functions as his “Tongue Prothesis”
Sometimes (like in the picture above) you can see a smaller male Parasite behind the female – this is how the “Cymothoa exigua” is mating. The young males will then resettle in a mouth of a fish and the circle restarts. I was lucky enough to capture that shot in Lembeh Strait in December 2012 – diving with the skilled Dive-Team of NAD Lembeh.