Garbage became home to octopuses. And there are plenty of houses for them at sea. Even a newly described species of the animal has only been documented in the midst of human waste that ends up in the ocean.
Brazilian researchers used 261 photographs taken by volunteers around the world and sought to catalog how octopuses use the waste that is widely available in the world’s seas. The study was published in the Marine Pollution Bulletin.
Bottles (broken or not), beverage cans and even car batteries end up becoming a home for these cephalopods. And, of course, the abundant plastics are also part of the dirt list.
The researchers were even surprised that plastic “houses” were not the most common among animals. Glass residences ranked first, accounting for more than 40% of documentation. But the explanation for this may simply be the fact that the glass, due to its density, reaches the seabed. Meanwhile, the plastics most commonly found in the sea are less dense than salt water and float and break down over time.
According to scientists, the glass could also have a more “cozy” shape as a shelter and have a texture more similar to the inside of shells.
Garbage ends up being used more by smaller animals and young animals, whereas the larger ones use rocks and corals.
“They are adapting to this new environment created by human pollution”, says Maira Proietti, a professor at the oceanography institute at Furg (Federal University of Rio Grande) and coordinator of the university’s marine litter project. “The first worrying point is realizing that the garbage is so abundant that the animals are considering it a suitable habitat. They are using it as a burrow, but they could also be ingesting this garbage.”
Octopuses are molluscs that have lost their shells. For this reason, they need external shells or other forms of protection and shelter. The problem, say the researchers, is that people usually pick up shells and that they also suffer from a process of sea acidification, which makes it difficult for these structures to calcify/form.
Depending on how you look at the situation, it may seem like a positive thing to give shelter to a living being. But the situation is more complex and needs further studies, say the authors.
Even a newly discovered by scientists, like the pygmy octopus paroctopus cthulu, already suffers the impacts. First described in 2020/2021 by Tatiana Silva Leite, professor in the department of ecology and zoology at UFSC (Federal University of Santa Catarina), and other researchers, the cephalopod has so far only been found in garbage caches. The discovery of the animal, even in Ilha Grande, Rio de Janeiro, happened when fishermen and divers were taking garbage from the sea; as cans were placed on the boat, animals began to come out of them.
According to Leite, between 80% and 90% of the octopuses’ time is spent inside their burrows, which, in the current oceanic scenario, means a good part of their life in the midst of garbage.
The use for housing — and even for laying eggs — of objects thrown into the sea also demonstrates something else in relation to octopuses: they are extremely adaptable animals. There are ancient reports of octopuses living inside amphoras and clay containers, says Leite. But the situation is now different.
“It does not mean that it is healthy to be in the garbage. We see human beings using garbage, but it does not mean that it is healthy. We do not know how pollutants are transferred to animals”, says the UFSC researcher.
Glass, for example, in theory, could have less potential for transferring contaminants to animals, but a broken glass (or a half-empty can) poses a risk of injury to animals.
In addition to their adaptive ability, octopuses are also intelligent animals, including the ability to use tools —using coconut shells as a hiding place, for example—, as we see in few animals on the planet (ourselves among them). Octopuses can also use whatever is available around them to close off the entrance to their den, even garbage.
The photos used for the study were taken in places with tourist activity and with the help of citizen science, that is, ordinary people capture images and pass them on to researchers. But there are records of octopuses interacting with garbage even in deep water, which can only be reached with underwater vehicles.
Thus, it is not possible to imagine that the results of what was found would be very different in other places. “To think of places untouched by garbage is practically impossible. Even extremely remote places will have garbage, because it will be transported by currents and winds”, says Proietti. “There is no more place untouched by garbage.”
With what he has been observing, Leite says it is important to warn people to be careful even when trying to do a good deed and remove the garbage from the sea, considering the possibility that this is the home of an octopus.
