In 1969, The Beatles wrote a song called Octopus's Garden. The idea for the song came when a ship captain told one of the band members how octopuses travel along the sea bed, picking up stones and shiny objects with which to build gardens. In 2022, a team of researchers from Italy and Brazil wrote a study with a title inspired by the Beatles song, in which they detail how octopuses interact with litter and sometimes even use it.
In an octopus's garden in the shade
Octopuses evolved over 300 million years ago, before the dinosaurs, and are some of the most intriguingly bizarre species on Earth. They can live in freezing water, in the depths of the oceans, and they're social in surprising ways. They're also highly intelligent and have a striking capacity to adapt. After all, we're talking about creatures that can shoot jets of water to switch off the lights at an aquarium.
In the new study, researchers looked at hundreds of crowdsourced photos of octopuses interacting with litter. They documented 24 species of octopus sheltering inside bottles and cans, using bottle caps and seashells, or even carrying plastic and glass pieces around to hide themselves from predators.
Researchers have known that octopuses can grasp and use objects for decades, but this is the first study to systematically characterize litter use. The results underline the animals' ability to use a variety of elements in their environment.
"The deep-sea records were extremely interesting, because even at great depths these animals are interacting with the litter," said Maira Proietti of the Federal University of Rio Grande in Brazil, who supervised the research, in a Yale press release. "They clearly see that there’s a lot of litter around, and it can therefore act as a kind of artificial camouflage."
"It shows their extreme ability to adapt. They are very intelligent animals, and they will use what they have at their disposal to continue sheltering or walking around with protection."
Overall, the octopuses seem to prefer unbroken, dark, or opaque items, which offer the most protection as a shelter. The most common use for rubbish was for shelter.
When seashells go out, rubbish goes in
Octopuses have been using seashells for defense and shelter for a long time, either for themselves or for their eggs. With seashells being picked and sold at the market, the animals have been forced to adapt. It's not a good thing that the animals are using litter as shelter because it suggests they are having trouble securing enough seashells for their needs. Overall, the researchers found that 40% of the interactions occurred with glass objects, while 25% were with plastic items -- presumably because glass resembles seashells more.
"We hypothesized that octopuses would interact mainly with plastic materials since this type of litter is highly abundant in marine ecosystems," the researchers write. "However, underwater images revealed that octopuses more frequently used glass items than plastic ones, mainly for sheltering."
Sheltering themselves or their eggs inside discarded rubbish (especially things like tires, batteries, or plastic objects) could expose octopuses to harmful chemicals reaching from the rubbish.
"Despite the possible positive impacts of using litter as shelter by octopuses, this interaction could have negative implications such as exposing animals to toxic compounds – such implications require additional investigation," the study authors write.
While the study had no control subject and we don't know how likely octopuses are to use rubbish compared to other species (or how species of octopuses fare compared to each other), it shows that crowdsourced images can offer useful insights when it comes to studying creatures that are typically out of human sight.
Ultimately, while it is pretty cool that octopuses are able to use the rubbish to their advantage, it would overall be much better if there was no rubbish in the sea for these critters to interact with.
"We emphasize that measures to prevent litter from reaching the ocean are essential to minimize its impacts: adequate waste management, public policies, international agreements, improvement of product materials/design, circularization of the plastic economy and public awareness are urgent measures to reduce litter impacts not only for cephalopods, but for all marine organisms and ecosystems."
The study was published in Marine Pollution Bulletin.