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The Tongue Thief is a small passive crustacean parasite in Subnautica 2 that lives in the runoff pools of the Karakorum Metal Farms. Its tentative species name is Ostrakonskelos glossaklept, literally the hard-legged tongue thief, a reference to its parasitic lifestyle. The Tongue Thief is not a player-facing threat in the usual sense; it does not damage divers and is classed as passive. Its role in the ecosystem is to parasitise the Epicurean, a larger crustacean it manipulates from inside the host's mouth.

Appearance and Habitat

Tongue thieves closely resemble Earth crabs and other members of Pancrustacea, with a segmented crab-like body and two trailing cerci that evolved from rear legs. Individuals are colored a faint light yellow, blending in with the runoff pools they inhabit. They are most often encountered in swarms around runoff pools within the Karakorum Metal Farms region, which is also where the Epicurean host species lives.

Parasitic Behavior

Individual tongue thieves swim deliberately toward Epicureans to be swallowed. After ingestion, a tongue thief evades the host's digestion by latching onto the Epicurean's tongue. From that anchored position the parasite secretes a numbing agent that blocks the host's nerves signalling satiety to the brain. The Epicurean never registers as full, which drives it to feed constantly and become noticeably more aggressive. The parasite gets a stable supply of nutrition from the host's increased intake, and in this sense the relationship is described in the in-game scan entry as semi-cooperative even though it remains parasitic.

Tongue thieves reproduce in place inside their host. Eggs or spermatophores are anchored in the host's mouth and wait until a thief of the opposite sex arrives. Newly-hatched manca pass out through the Epicurean's digestive tract and disperse to find their own hosts.

Removing a Tongue Thief

A tongue thief can remain attached to its host indefinitely, but it can be expelled by the player using the Sonic Resonator. The Survival Multitool does not work for this purpose; only the Sonic Resonator's pulse can dislodge the parasite. Expelling the tongue thief reduces the host Epicurean's hunger-driven aggression.

Real-World Inspiration

The Tongue Thief is a direct nod to Cymothoa exigua, the Earth isopod commonly called the tongue-eating louse, which similarly parasitises fish by living in the mouth and even replacing the host's tongue. The Subnautica 2 design borrows the parasite's location and feeding mechanism, then adds the satiety-blocking chemistry and the gameplay loop around removing it.

In-Game Notes

The Tongue Thief is scannable for the Databank, which records its species name, body plan, parasitic hijack, and the cultural-function speculation found in the in-game entry. Players who want to keep Epicureans from becoming hyper-aggressive in a given area should periodically clear any host carrying a tongue thief; the immediate decrease in feeding pressure is the main observable effect of the cleanup.