Study reveals annual activity of sneezing sea sponge off B.C. coast

Image of Belinda the sea sponge underwater is shown in this handout image provided by Ocean Networks Canada. A study into the behaviour of a sea sponge off the coast of British Columbia has revealed the animals possess the ability to sneeze. THE CANADIAN PRESS/HO-Ocean Networks Canada

A study into the behaviour of a sea sponge off the coast of British Columbia has revealed the animals have the humanlike ability to sneeze.

Researcher Sally Leys said her team examined footage captured over a span of four years by eight cameras installed on the sea floor by Ocean Networks Canada in an effort to study the sponge's response to the changing climate and weather patterns.

She said they observed the sponge performing regular “sneeze-like” contractions lasting upwards of a day at a time to clear debris that accumulated while it was filter feeding.

"If you put dirt onto the sponge … it's an irritant to the system, and it has to get rid of it, so it wraps it up in mucus, and it pumps it through and out it goes," she said in an interview. "But it's a slow sneeze."

Leys said the smaller the sponge, the quicker the sneeze.

"A little, tiny sponge — they're about an hour, maybe 40 minutes, for a sneeze, and then for Belinda, it's like a day."

Belinda was the nickname researchers gave to the sea sponge they focused their study on, which Leys noted is about the size of a fist.

She said it was "a pretty active critter," although if a diver went down to view the sponges in their natural habitat — like a plant in the garden — it would seem unmoving.

Long-term monitoring of the animals proved otherwise, she said.

"I was blown away of how active it was," Leys said. "This thing was bouncing up and down, and doing all kinds of things."

Leys, who is a professor in the faculty of science at the University of Alberta, said the experiment tracked the animal over daily, yearly and seasonal changes in shape, colour and size.

Hundreds of hours of video was collected between 2012 and 2015 from the research site about 25 metres under the surface off the Vancouver Island coast. Leys said researchers then spent the next decade analyzing the data.

The study, recently published in Marine Ecology Progress Series, highlighted the sea sponge's response to its changing environment, she said.

Leys said she was "most surprised" by the sponge's "annual behaviour."

She said the sponge contracted to half its size, and entered a dormant state during winter months, despite lacking muscles and a nervous system.

"It suggests the mechanism doesn't require nerves to withdraw. Once you stop feeding, once there's less food, there's sort of an innate response," she said. "The really interesting question (is) how this animal reduces its activity in response to less food by becoming smaller."

The study said the sneezing behaviour was observed during the summer months, when phytoplankton blooms increased particulates in the water as the sponge regained its shape.

Ley said studying behaviours will allow researchers to better understand how sponges respond to changes in their environments.

This study marks the longest continuous recording of the animals in the wild.

Although the camera array was removed in 2015 with the conclusion of the project, Leys said divers have confirmed as recently as two months ago that Belinda remains at the site, and is healthy and back to its original colour.

Leys said she is hopeful that researchers will reinstall the cameras to continue the study as ongoing monitoring could reveal even more about how sea sponges respond to changing ocean conditions.

"I'd like to see 10 years of dormancy, then we would be completely sure of this pattern that goes on," she said.

"I think that having cameras back down there would allow us to really get a long-term view of why it's undergoing these different kinds of behaviours, whether they are very predictable, and I think, in the long run, it would allow us to understand whether it correlates with changes that we see in the bigger picture of the ocean."

This report by The Canadian Press was first published Jan. 7, 2025.