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Sticker of Tongue-eating louse
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Tongue-eating louse

Cymothoa exigua
Eats: It lives off other animalsWoodlicePonds, rivers and shores14 legsNot an insect, but a bug cousin

The tongue-eating louse is a sea cousin of the woodlice you find under stones. It has a flat body made of segments and 14 sharp legs. It lives inside the mouth of a fish and does a very strange job: it takes the place of the fish's tongue.

Fun fact: woodlice are not insects. They are crustaceans, cousins of crabs and shrimps, that live on land.
Lives in
The Atlantic and Pacific Oceans, along the coasts of the Americas
Length
0.8 to 2.9 cm (0.3 to 1.1 in)
Top speed
about 0.23 km/h (0.14 mph)
On foot, estimate
Can it hurt you?
Harmless
It lives only on fish and is not a danger to people.
What does it eat?
It lives in a fish's mouth and feeds on the fish's blood and slime.
For real!Photo of Tongue-eating louse
Picture by Marco Vinci. CC BY-SA 3.0, via Wikimedia Commons.

How big is it?

How long is it?

Tongue-eating louse about 2.9 cm long (1.1 in)A grain of rice about 6 mm (0.24 in)A toy building brick about 3.2 cm (1.3 in)A crayon about 9 cm (3.5 in)
as long as 5 grains of rice in a rowit has about 14 legscould run across a dinner table in 16 seconds

How big is Tongue-eating louse compared to YOU?

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How fast is it?

cool stuff

Fun facts

1

It is the only animal known to take the place of a body part of another animal.

2

The fish can still use it like a tongue to hold its food.

3

Every one starts life as a male, and some turn into females later.

4

It can live for up to three years and grows together with its fish.

5

A mother carries more than 400 eggs in a pouch under her body, like all woodlice do.

you asked

Most asked questions about Tongue-eating louse

?Is the tongue-eating louse dangerous to people?

No. It only lives in the mouths of fish.

?What does the tongue-eating louse do?

It gets into a fish's mouth through the gills, holds on to the tongue until the tongue is gone, and then works as the fish's new tongue.

?How big is the tongue-eating louse?

Females are 8 to 29 millimetres long, and males about 7.5 to 15 millimetres.

For bug experts

Scientific name
Cymothoa exigua
Group
Woodlice
Family
Cymothoidae
Classification
Malacostraca > Isopoda > Cymothoidae
Lives on
North America, South America

Where the facts come from

  1. Cymothoa exigua (Wikipedia, CC BY-SA 4.0): what it looks like, where it lives, what it eats, sizes and fun facts, retold in simple words.
  2. Picture by Marco Vinci. CC BY-SA 3.0, Wikimedia Commons. The round sticker of this bug is cut from the same picture.

If we got something wrong, sorry, we are bug fans, not a science journal. Tell us at hello@bugwiki.app and we will fix it.

More from the same group: Woodlice

Also at home here: Ponds, rivers and shores