A study found that sea turtles do not just accidentally swallow plastic drifting in the ocean but can respond selectively depending on color and texture. In particular, the more mature the individual, the more sensitively it responded to bright and soft plastic, suggesting an important clue for devising measures to reduce marine plastic.
The team led by senior researcher Hong Sang-hee at the Korea Institute of Ocean Science & Technology (KIOST) said it confirmed this pattern after observing behavioral responses by color to identify why sea turtles ingest plastic. The findings were published in Scientific Reports in Feb.
The researchers conducted experiments on hawksbill sea turtles bred artificially at Aqua Planet Yeosu. Eight 4-year-old individuals and 27 10-week-old individuals took part in the experiment. The team simultaneously presented each turtle with plastic packaging in six colors—transparent, white, blue, red, yellow, and black—and then compared and analyzed pecking or biting responses with the beak.
As a result, the 4-year-old individuals showed higher responses in the order of transparent, white, and yellow. In contrast, no clear preference was observed for blue. The 10-week-old juvenile sea turtles showed no significant differences by color and tended to respond relatively randomly to surrounding objects.
The researchers interpreted this difference as a variation in prey recognition ability by growth stage. Individuals with accumulated feeding experience are highly likely to perceive bright and soft plastic as natural prey such as jellyfish and respond selectively. In contrast, juveniles may not have sufficiently developed prey discrimination abilities and thus can be indiscriminately exposed to various plastics.
This study was conducted based on prior research that examined the visual responses of sea turtles using jellyfish dyed with food coloring. The team noted that it is especially significant in that it analyzed sea turtle behavior using plastic actually found in the ocean.
Hong said, "This study is the first behavioral experiment using plastic found in the actual ocean, and it is significant in that it approached the causes of plastic ingestion by marine-protected species from a behavioral perspective," adding, "Through follow-up research, we will more systematically identify the causes of biological damage caused by marine plastics and, based on this, establish a scientific foundation for effective response measures."
References
Scientific Reports (2026), DOI: https://doi.org/10.1038/s41598-026-39765-0