One of the most interesting crustacea found along the South African coastline has to be the Tongue-eating louse (Cymothoa springbok), a newly described South African species by Prof Nico Smit and his team. This is a massive female in the mouth of a carpenter (Argyrozona argyrozona), off Struisbaai. They are a species of isopod and all are born male. Free drifting in the ocean they find a host fish and enter through its gills. The males attach themselves to the gill arches until one is old enough to change sex to female. Thereafter it moves onto the host fish's tongue where it bites on and stops the blood circulation, causing the host's tongue to disintegrate. The louse then replaces the function of the host's tongue and survives off the nutrient-rich blood and mucous supplied to the host's tongue. This form of symbiosis is closer to commensalism but unfortunately, the fish does lose blood to the louse so it’s technically parasitism. Besides the insignificant blood loss, there is no other harm caused and the louse should not be removed from the fish's tongue. The louse dies when the fish dies, so there is no evolutionary advantage of this louse starving his host of food or blood. So for both species to complete their lifecycles a healthy relationship is maintained.