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The tongue-eating parasitic louse is a terrifying creature that invades the mouths of fish and feeds on their tongue, eventually replacing it. This parasite causes serious damage to the host fish, causing problems with feeding and breathing. However, some fish have developed ways to detect and remove these parasites, such as shaking their heads or rubbing their mouths on the seafloor. Despite these defenses, the tongue-eating louse can still be a threat to many fish species, and its presence can have significant impacts on fish populations and ecosystems.
Wild Animals
Parasites are generally not well-regarded, but not all organisms that live off others are the same. Some parasites take food from others, some force animals to raise their young, and some use other organisms for transportation. However, some parasites kill their hosts slowly, drain their life force, or even control their actions. It is uncommon for a parasite to consume and replace a body part of its host, but this is a strange world and evolution has experimented with many things.
Artificial Parasites
For example, the parasitic isopod Cymothoa exigua parasitizes fish. This crustacean, which resembles a terrestrial crustacean called a roly-poly or sow bug, lives in the ocean and feeds on several species in the perch family, mostly snappers and drums. Although its lifestyle may seem a bit extreme for humans, Cymothoa exigua attaches itself to a fish’s tongue, feeds on its blood until it falls off, and then takes its place as a prosthetic tongue for the rest of the host’s life.
“Now it can eat what the fish eats or consume its blood and tissue,” said Regina Wetzer, Curator and Director of the Marine Biodiversity Center at the Natural History Museum of Los Angeles County.
While there are other isopods that infest the mouths of fish, such as barramundi or mahi-mahi, Cymothoa exigua is the only one known to science that eats and replaces the tongue.
Protandric Hermaphrodites
“Cymothoidae isopods are fish parasites, and all cymothoids must find and attach to their hosts as juveniles,” says Wetzer. “In the case of Cymothoa exigua, the species attached to the tongue, males enter the body through the gills, mature, mate, and then females migrate to the tongue.”
So how do females enter the fish if only male juveniles enter the gill slits? Cymothoa exigua is a protandric hermaphrodite, meaning it can change from male to female once it reaches adulthood. In other words, all individuals are born male, and as a juvenile enters a fish’s gills, it continues to mature as a male. However, when another male juvenile arrives, the first one receives a signal to transform into a female. Once the female has replaced the tongue, she is free to mate with any males in the fish’s gill chamber and raise her babies in a safe cave.
The Cymothoa exigua, also known as the tongue-eating louse, is a type of parasitic crustacean belonging to the Cymothoidae family. It infiltrates a fish, such as the sand steenbras Lithognathus mormyrus, through the gills and attaches itself to the fish’s tongue.
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Instructions for Substituting a Tongue
The Cymothoa exigua is a robust and powerful crustacean equipped with seven pairs of legs armed with spines that help it anchor itself into the mouth of the fish. The first step in the process is to use its five sets of jaws, modified with a variety of ice-pick-like tubes, to puncture the fish’s tongue and suck out its blood. This process, however, is not believed to be a pleasant experience for the fish.
As the isopod feeds on the fish’s blood, the tongue muscle degenerates and shrinks away. At this stage, it seizes what is left of the tongue stub with three or four of its spined leg sets and takes over the function of the tongue entirely.
Although it is unpleasant, these isopods generally do not kill their host. Nonetheless, the Cymothoa exigua cannot survive without a host.
“Fully mature isopods would not survive well without their host because they are obligate parasites,” says Wetzer. “They have poor swimming abilities, and gravid females—females carrying eggs and juveniles in their pouch—are especially non-agile. This is in contrast to other species [of the same isopod family] that are free-living and can occur in such large numbers that they can strip a fish or a body entirely of flesh.”
Now That’s Interesting
Fish use their tongues to push food backward toward their throat, while mammals use tongue muscles to position food for chewing.
FAQ
1. What is a tongue-eating parasitic louse?
A tongue-eating parasitic louse, or Cymothoa exigua, is a type of crustacean that lives in the mouths of certain fish species. It enters through the gills and attaches itself to the base of the fish’s tongue, cutting off its blood supply and causing it to wither away. The parasite then takes the place of the tongue, feeding on the fish’s blood and mucus.
2. How does the fish survive with the parasite?
The fish is able to survive with the parasite because the louse acts as a replacement for the tongue. It continues to feed on the fish’s blood and mucus, but doesn’t cause any significant harm beyond the initial loss of the tongue. In some cases, the fish may even benefit from the parasite’s presence if it eats the louse’s feces, which can contain undigested pieces of food.
3. What happens to the parasite after the fish dies?
After the fish dies, the parasite detaches from its host and swims away in search of a new one. However, because the louse is highly specialized and can only survive in the mouths of certain fish species, it may have difficulty finding a suitable host. This can be particularly challenging if the parasite has attached to a non-native species that it cannot survive on.
4. Are there any benefits to having a tongue-eating parasitic louse?
While there may be some benefits to having a tongue-eating parasitic louse in terms of the food it provides, most fish do not want this parasite in their mouth. The loss of the tongue can make it difficult for the fish to feed properly, and the louse’s presence can be uncomfortable or even painful. Additionally, the parasite can cause long-term damage to the fish’s mouth if it remains attached for an extended period of time.
5. Is it possible for humans to contract a tongue-eating parasitic louse?
No, it is not possible for humans to contract a tongue-eating parasitic louse. This particular species of crustacean is highly specialized and can only survive in the mouths of certain fish species. While there are other types of parasites that can affect humans, such as tapeworms and lice, they are not the same as the tongue-eating parasitic louse.
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