The most well-known parasite that attaches to the tongue is Cymothoa exigua, often referred to as the tongue-eating louse. This remarkable creature is a parasitic isopod notorious for its unique method of parasitism on fish.
Understanding the Tongue-Eating Louse (Cymothoa exigua)
Cymothoa exigua belongs to the family Cymothoidae and is a fascinating example of extreme parasitism in the animal kingdom. These invertebrates are commonly known as "tongue biters" due to their unusual behavior.
As isopods, they are crustaceans, distantly related to familiar land-dwelling pill bugs. They exhibit sexual dimorphism, with females generally growing larger than males:
| Characteristic | Female Size | Male Size |
|---|---|---|
| Length | 0.3 - 1.1 inches | 0.3 - 0.6 inches |
Life Cycle and Impact on Host
The life cycle of Cymothoa exigua is quite specialized:
- Entry: The juvenile parasite typically enters a fish through its gills.
- Attachment: Once inside, it migrates to the fish's mouth and firmly attaches itself to the base of the tongue.
- Blood Feeding: The parasite then begins to feed on the fish's blood vessels within the tongue.
- Tongue Atrophy and Replacement: As the parasite feeds, the fish's tongue gradually atrophies due to lack of blood flow and eventually deteriorates. Cymothoa exigua then effectively replaces the tongue, becoming a functional prosthetic for the fish. The fish can then use the parasite as if it were its own tongue, allowing it to continue feeding and surviving.
While the presence of Cymothoa exigua can weaken the host fish, it typically does not directly kill it. The fish can often continue to live and feed with the parasite acting as its tongue. However, an infected fish may experience reduced growth rates and overall poorer health.
Geographic Distribution and Human Interaction
Cymothoa exigua is primarily found in marine environments, particularly in warmer waters of the Eastern Pacific Ocean, from the Gulf of California south to parts of Ecuador. They parasitize various species of fish.
It's important to note that while Cymothoa exigua can be startling to observe, it poses no known threat to humans. These parasites are fish-specific and cannot survive or reproduce on humans. Instances of them detaching from fish and biting humans are rare and usually cause only minor, temporary discomfort.
For more information, you can explore resources like National Geographic's overview of the tongue-eating louse.
