A sea sponge observed off the coast of 91原创 Island for more than four years was found to both hibernate and “sneeze” in behaviours thought to expel waste and adapt to a changing ocean — useful traits for an ancient animal that has no muscles and no nervous system.
The , carried out by researchers at the University of Victoria and University of Alberta, involved a tennis-ball-sized Suberites concinnus sponge whose evolutionary family evolved 600 to 800 million years ago.
Sally Leys, a professor in the University of Alberta’s Department of Biological Sciences who nicknamed the sea sponge Belinda, said the species act as “ecosystem engineers” — filtering out plankton and pooping out particles big enough for other animals to eat.
“Why Belinda?” said Leys. “You better give it a name or you’re going to get a SpongeBob.”
Placed at the focal point of a camera array 23 metres under the surface of Barkley Sound, scientists were able to continuously track environmental conditions and monitor how the sponge reacted.
Sponges feed by filtering bacteria and particles out of sea water in quantities that can reach 1,000 times their volume every hour.
When the researchers observed Belinda, they found the sponge “exhibited remarkable” rhythmic contractions that appeared to be responding to “unidentified triggers.”
Every winter for two months, the sponge was found to contract to almost half its size. But by February, it started to expand again, often shuddering with full-body contractions, or sneezes, lasting 11 hours at a time throughout the summer.
First documented case of sponge ‘hibernation’
A previous study had found the sponge decreased in size and activity before the arrival of a big storm. In the latest research, the sponge’s movements were found to be associated with pressure, chlorophyll and water turbidity — indicators the researchers suspect are linked to winter low-pressure systems, decreased food availability and the accumulation of too much debris from sea water.
The researchers concluded that the reduced size of the sponge during winter months represented a kind of dormancy period triggered by a lack of food, decreased sunlight and storms. But what sets the sponge into a full-blown sneeze “remains unknown” and will require controlled lab experiments to understand, said Leys.
Dominica Harrison, a PhD student at UVic and the study’s lead author, said the research shows how observing the natural world over long periods of time catch things never seen before.
“This is the first time that we actually showed that they hibernate,” said Harrison. “That’s important because sponges are kind of the base of the food web.”
“This is our cleaning mechanism for the ocean.”
And if one day the sponges wake up early, that will be a signal that something is off, said Harrison.
“We can use their behaviour as a canary in the coal mine, a sentinel for climate change,” she said. “One change in one organism can ripple throughout the ecosystem.”
A hardy sponge in hot water
Throughout Belinda's hibernations, observations showed a small part of the sponge remained puffed up, an area Leys suspects acts as a sensor — like a thermostat on a heat pump or furnace — constantly testing the water to see if she should should kick on the pumps and start feeding.
“They’re not smelling with their nose. But they're definitely able to detect variations in chemicals, and certainly fluid movement, which is probably vibration,” she said.
The study also found Belinda reacted to multi-year changes in water temperature. Between 2013 and 2016, a marine heat wave known as the ‘Blob’ raised surface sea temperatures across large stretches of ocean off the west coast of North America.
Over that time, Belinda was observed changing colour “significantly” from smooth-surfaced pale orange-yellow to a dark orange and lumpy surface.
The team’s camera system was removed from the platform at the end of 2015. In 2022, when divers carried out routine maintenance, they found the sponge had returned to its pale-yellow smooth self seen a decade earlier.
The researchers found the creature’s ability to bounce back — and potentially live more than 100 years old — demonstrates just how resilient the species is to change.
“I was really amazed,” said Leys. “How does it tolerate such a massive change in temperature?”
“How does it get over that and keep going?”
