These Creepy Little Creatures Live Inside The Mouths Of Fish, Replacing Their Tongue


This dreadful parasitic isopod dwells in fish mouths, replacing their tongues and feeding on their blood. While we’ve already featured some extremely horrific aquatic species, such as the Atlantic wolffish and the sardonic fringehead, the tongue-eating louse may be the creepiest of them ever.

The Cymothoa exigua, often known as the tongue-eating louse, is an isopod (a kind of animal that includes crabs and shrimp) that spends most of its existence within the mouths of various fish.

They have been observed removing the tongue and replacing it with themselves. In fact, the tongue-eating louse is the only parasitic parasite known to replace a whole organ of its host. Female lice may grow to be around an inch (2,5 cm) long, but male lice are generally about half that size.

However, there is a catch: every Cymothoa exigua begins as a male, but after they have established themselves within a fish and completed their development process, they swap sexes and change into a female. This happens only if the slot isn’t currently occupied by a girl.

The parasitic trip begins with the tongue-eating louse entering the fish through the gills (this is actually how most fish parasites get into their hosts). After successfully entering the fish, the louse rises to the base of the tongue and prepares for its lengthy stay within.

It first clamps its powerful legs onto the tongue, locking itself in the fish’s mouth. This is where things turn nasty: the parasite pierces the tongue, cutting off the bl.o.od flow to the tongue.

This causes the fish’s tongue to atrophy and finally fall off, leaving the fish with only a stump. The louse then attaches itself to the injured organ, functioning as the fish’s prosthetic tongue, and feeds on mucus and blo.od.

Surprisingly, this does not k.i.ll the fish since it is in the parasite’s best interest for the fish to live as long as possible. In fact, the fish may use the louse as an organic tongue prosthesis, capable of fulfilling all of the responsibilities and functions that a real tongue can — while being somewhat horrific.


So, despite the presence of a big isopod in the fish’s mouth, it may lead to a somewhat normal existence. If it wasn’t disturbing enough, it gets much crazier.

Remember how juvenile Cymothoas become females when they migrate in? If a fish is already caught, they remain in the gills of the fish and mature into males. Once the female and male have matured into fully-fledged louse, the male creeps into the female’s mouth and mates.

Yikes. After a brief gestation time, the female gives birth to a new generation of lice, continuing the nightmare cycle. Little is known about what the louse does once its host

Maybe it gives up on life with the fish, but it might also separate from it and start looking for a new home. The tongue-eating louse’s primary prey are snappers, although it has been detected in other fish species as well.

If you’re wondering if these parasites are harmful to people, there’s good news. Except for biting your finger if you try to contact it, the Cymothoa exigua presents no significant threat to humans.

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