Oceanic Odyssey or Ecological Nightmare: A Crab Trapped in a Bottle Drifts for 2 Months

Japanese researchers have recently described an oceanic odyssey as improbable as it is unsettling, involving a crab that apparently grew inside a plastic bottle.

Plastic Prison

The crustacean and its vessel had been discovered in 2022 off the coast of the Okinawa archipelago. “We came across this plastic bottle about half a kilometer from the shores of Sesoko Island,” the authors of the new study, published in the journal Ecosphere, write. “To our great surprise, a living and fairly sizeable swimmer crab was found inside.”

Belonging to the species Portunus sanguinolentus, it measured 4 centimeters in length and 8 in width, while the bottle neck did not exceed 2.4 centimeters in diameter. Obviously, it could only have slipped in when it was considerably smaller, which also implied sufficient food resources to sustain its growth.

Once the animal was freed from its plastic prison, genetic sequencing showed that it had recently consumed the fry of Canthidermis maculata and Abudefduf vaigiensis, as well as algae that had grown on the bottle’s inner walls.

Based on the size of its principal occupant and that of a specimen of Lepas anserifera, a filter-feeding crustacean known for attaching to the carapaces of crabs and for rapid growth, the Japanese team estimated the duration of this odyssey at two months.

Des polluants omniprésents

If this seemingly unlikely discovery echoes a Japanese folk tale from the late 1920s, in which a salamander proves unable to leave its cave after spending two years feasting there, it mainly highlights the scale of plastic pollution.

“Similar reports in Japanese waters indicate that this is not an isolated phenomenon,” the researchers write. “Objects that simplify our daily lives can have devastating effects on marine life, no matter how resilient it may be.”

Last year, a study revealed the presence of such pollutants at the deepest point of the Mediterranean Sea.