Cymothoa exigua, or the tongue-eating louse, is a parasitic crustacean of the family Cymothoidae. It tends to be 3 to 4 centimetres (1.2 to 1.6 in) long. This parasite enters through the gills, and then attaches itself at the base of the spotted rose snapper’s tongue. It extracts blood through the claws on its front, causing the tongue to atrophy from lack of blood. The parasite then replaces the fish’s tongue by attaching its own body to the muscles of the tongue stub. The fish is able to use the parasite just like a normal tongue. It appears that the parasite does not cause any other damage to the host fish.


Crustaceans belong the the subphylum Crustacea, and are members of the invertebrate phylum Arthropoda

Like other arthropods, they have an exoskeleton, which does not grow with them, and which they must moult in order to grow larger. They have two-part legs (other arthropods have one or three-part legs), though the number of legs varies greatly between species.

The commonly-known species of crab, lobster, shrimp, crawfish, and barnacles all belong to the Crustacea subphylum, but they’re not alone - there are more than 61,000 species of Crustacean, and they’ve existed since the Cambrian period, 500 million years ago.

Though most crustaceans are motile and aquatic, there are some that are partially terrestrial, barnacles are sessile (non-moving) as adults, and a few  are parasitic, such as the whale and fish lice, and bizarre tongue-eating louse (Cymothoa exigua).

Nouveau Larousse. Pierre Larousse, 1898.

Mystery tuna creature is tongue-eating parasite, says expert

The tiny creature discovered in a tin of tuna by a Nottingham mother is a tongue-eating louse, scientists believe.

Zoe Butler was amazed to find a pair of eyes staring up at her when she opened the can of Princes tuna chunks.

The tiny tuna monster has set Twitter abuzz with explanations. The search for answers has been dubbed #tunagate.

But the Natural History Museum said that the head probably belonged to a Cymothoa exigua, or tongue-eating louse. The parasite lives inside a fish, entering through its gills and attaching itself to its host’s tongue.

Stuart Hine, Identification and Advisory Service manager, from the Natural History Museum, in London, said: “‘From what I can see I would support the head of a Tongue-eating louse, Cymothoa exigua, or similar.

“I think these are associates of smaller fish than Tuna and fish that tuna eat.
“We could undoubtedly say more if presented with the specimen .’



Family: Cymothoidae

‘Fun’ Fact:  This creature enters a fish’s body through its gills, attaches itself to the base of the fish’s tongue and extracts blood from the tongue with its claws. In fact, this isopod drinks so much blood that the tongue atrophies away, starved of all nutrients. Then it replaces the tongue by attaching itself to the muscles of the exposed tongue stub. The fish uses the louse as if the parasite were its very own tongue.

tongue-eating louse head found in can of tuna. this louse is an isopod, like a wood louse, and is known to cut off the circulation from the tongue of a fish, causing the tongue to eventually fall off (a painless process for the fish). once this happens the louse attaches its body to the muscles left in the stub of the tongue and acts as the tongue - even allowing the fish to use the louse as a functional tongue.

from here and here

OC October: Day 9

Isopod sisters Jeot and Gall. Both of them serve the Crustaceanauts, although the reason for this affiliation is unknown. Jeot uses arcane magic to manipulate her foes while Gall prefers to take a more direct approach and infest them the old-fashioned way - taking up residency in their mouths, disabling most of their higher brain functions, and puppeteering them. Her sister was once just as adept at this, but a strange illness has left her frail and unable to do so.