Laboratory studies suggested filter feeders like barnacles do pick up plastic pellets, but only three examples of plastic-eating invertebrates were known in the wild. (Sandhopper amphipods, or sand fleas, the Norway lobster and flying squid, for those keeping score.)
The researchers collected barnacles of two species, Lepas anatifera and Lepas pacifica, on two separate trips to the gyre. They then conducted barnacle autopsies, checking the digestive systems of the animals for microplastics, or plastic pieces worn by wind and waves to less than 0.2 inches (5 millimeters) in diameter.
Of the 385 barnacles collected, 129 had ingested plastic, the researchers found. Most of those individuals had a pellet or two in their gut, but 57 had more than three pieces, with one containing a whopping 30 individual plastic particles.
Researchers aren't sure whether these particles are affecting the barnacle's health; there were no signs of digestive backup in this group, at least. The long-term effects are unknown, they wrote.