Costello the octopus was napping glued to the glass of his tank at Rockefeller University in New York. She slept silently for half an hour and then entered a more active sleep stage, her skin varying through colors and textures used for camouflage, typical cephalopod behavior.
But soon things turned strange.
A minute later, Costello scuttled along the glass toward the sandy bottom of his tank, curling his arms around his body. He then he spun like a writhing cyclone. Finally, Costello swooped in and misted half his tank in ink. As the tank’s filtration system cleaned out the ink, Eric Angel Ramos, a marine scientist, noticed that Costello was gripping a pipe with unusual intensity, “it looked like he was trying to kill it,” he said.
“This was not normal octopus behavior,” said Dr. Ramos, who is now at the University of Vermont. It’s unclear when or if Costello woke up during the episode, Dr. Ramos said. But later, Costello returned to normal, eating and then playing with his toys.
“We were completely flabbergasted,” said Marcelo O. Magnasco, a Rockefeller biophysicist. Perhaps Costello was having a nightmare, he and a team of researchers speculated. They shared this idea and other possible explanations in a study uploaded this month to the bioRxiv website. It has yet to be formally reviewed by other scientists.
After the incident, Dr. Ramos reviewed footage of Costello’s activity, which was recorded as part of a behavior and cognition study (the lab was also looking at another octopus, Abbott; both were named after the heptapod aliens in the film “Arrival”). . In all, the team found three shorter instances that looked similar.
For Dr. Magnasco, the behaviors exhibited in Costello’s longest spell evoked the performance of a dream. Her arms curled around his body looked like a defensive posture, he said. In the footage, the animal is seen perhaps trying to appear larger, and then attempting an evasive maneuver: inking. When he fails to escape, Costello appears to be seeking to quell a threat by strangling the pipe, Dr. Magnasco said, adding: “This is a fight sequence.”
But he also acknowledged that “this is an isolated case in an animal that had its own peculiarities.”
There are other explanations for the behavior, such as a seizure or neurological problems, that could be related to Costello losing parts of two limbs before he was caught. But Dr. Magnasco said he hoped that when reporting the incident, other scientists would be aware of the behavior, which his group observed by chance.
Tamar Gutnick, a neuroethologist at the University of Naples Federico II in Italy who was not part of the study, said the researchers needed to address questions in the peer review, such as one about what happened at around the same time the next day. His colleague at the same university, Michael Kuba, a marine behavioral biologist, also said they needed to detail Costello’s typical sleeping behavior.
The study researchers said they could account for such queries, as they have images from the octopus’s entire life in the lab.
Another problem with interpreting the behavior of this octopus, Dr. Kuba said, is that Costello “was not completely cheerful and healthy”: the animal had stomach parasites.
Dr. Kuba suggested that some of the behaviors, such as arm curling, could have been the result of cramps, perhaps due to a problem with Costello’s digestive system or parasites reaching a part of his nervous system. Similar behaviors occur in captive octopuses, and are generally related to stress or age, he said. Costello died about six weeks after the longest episode.
Still, the idea of dreaming about octopuses is compelling, Dr. Gutnick said. Rockefeller’s team is not the first to put forward the idea that cephalopods dream as they go through different sleep phases. Because octopus body patterns are controlled by the brain, researchers have wondered if patterns during sleep might be responses to repeated dream-like events.
In their own research, Dr. Kuba and Dr. Gutnick recently recorded electrical signals from the brain of an octopus. That opens up the possibility that researchers could pry into the brain activity of octopuses during sleep and perhaps connect behaviors and body patterns during sleep with changes in brain waves to study processes related to dreams.
But that’s not necessarily related to this observation, Dr. Gutnick said, adding: “You have to show that they have dreams before they think of nightmares.”