Divers find tiny creature living on clam’s tentacle. It’s a new species in Japan
Just off Sugashima Island off the coast of Japan, researchers encountered an “unusual” crustacean no bigger than the width of a dime sitting on the tentacle of a Limaria hirasei, or file clam.
Upon closer inspection, more of the tiny shrimplike creatures were found living inside the clam’s shell.
The team has now confirmed they represent a new amphipod species called Leucothoe limidicola, according to a study published Sept. 26 in the peer-reviewed journal Zootaxa.
Though they may look like a shrimp, amphipods are not closely related.
In life, Leucothoe limidicola has a mostly white and vermilion body with the occasional “snowflake pattern” on its side, researchers said.
The species’ eyes are “white to pale vermilion,” and its appendages range from “pale pink to colorless.”
According to researchers, the Leucothoe genus most often live on sedentary invertebrates including sponges and bristle worms and associations with bivalves is “rare,” exhibited by just six of 206 Leucothoe species.
To test whether this unusual relationship was a fluke or something more complex, researchers separated the Leucothoe limidicola from the file clam.
The tiny shrimp-like crustaceans quickly returned to the clam, suggesting a strong relationship with the host species.
Researchers said this is an example of commensalism, an association between two species in which one benefits from the association without impacting the fitness of the other.
All specimens of the new species were collected from a single host file clam, the study said.
The clam was found under a rock about at a depth of about 30 feet, researchers said.
The research team included Tomoya Hanaoka, Ryutaro Goto, Hiroki Nakajima and Masafumi Kodama.
This story was originally published October 2, 2025 at 4:37 PM with the headline "Divers find tiny creature living on clam’s tentacle. It’s a new species in Japan."
