Parasite Turns a Fish’s Mouth Into a Working Tongue
A tongue-eating isopod, Cymothoa exigua, enters a fish through its gill slit, attaches to the tongue, and feeds until the tongue withers away, after which it sits on the bone where the tongue used to be and functions as a replacement tongue for the fish—allowing the fish to eat while the parasite reproduces. Scientists debate whether the replacement is a true, complete substitution or a partial one, but the arrangement is a rare, striking example of a parasite manipulating a host.