Tongue-eating louse

Cymothoa exigua

The tongue-eating louse is a parasitic isopod that enters a fish through the gills. It attaches to the tongue, causes the tongue to wither, and then occupies its place.

Not a fish · an aquatic neighbor

Water

Saltwater

Marine waters associated with reef and coastal fishes.

Temperature

Range not established

A dependable species-specific wild temperature range was not established from the reviewed sources, so both values are null.

Size

Up to about 3 cm (1.2 in) long

About the length of a paperclip

Lifespan

Best-supported wild lifespan is not established.

Life expectancy varies with place, conditions, and what scientists have been able to observe.

01 · Signature adaptation

What does it do?

A juvenile enters through the gills and changes sex as it matures. The female anchors to the tongue while the male usually remains behind her in the mouth cavity.

Its superpowerIt can function as a living replacement for a fish’s lost tongue.

02 · Home coordinates

Where does it live?

Eastern Pacific coastal waters, especially around host fishes such as snappers.

Regions: Eastern Pacific · Tropical and subtropical coastal waters

03 · The menu

What does it eat?

It feeds on blood and fluids from the host fish while remaining attached in the mouth.

Blood-feeding parasite: fish blood, host tissue fluids.

04 · Remember this

Two wow facts

Tongue substitute

After the fish tongue shrinks, the attached female isopod can act as a functional replacement.

Sources [1]

Sex-changing parasite

Young individuals mature as males and may later become females depending on social conditions.

Sources [1]