Belinda the surprisingly busy sea sponge takes a whole day to sneeze
Four years of time-lapse footage off B.C. reveals the unexpectedly active life of an inanimate animal
Belinda the sea sponge has a lot going on for an animal that can't go anywhere.
Canadian researchers have used four years of time-lapse footage from the sea floor of British Columbia to paint a picture of "the daily life of a busy sponge," says University of Alberta marine scientist Sally Leys.
While watching a sea sponge in real time can be "rather boring," Leys says the footage shows Belinda is, in fact, "extremely active," bobbing and twitching, receiving visitors, protecting itself from threats, and altering its shape and colour to adapt to changes in its environment.
"It's a very charismatic sponge," Leys, co-author of a new study about Belinda, told As It Happens host Nil Köksal.
The findings, by researchers at the U of A and the University of Victoria, were published recently in the journal Marine Ecology Progress Series.
"Just goes to show that there is no such thing as a 'primitive animal,'" Verena Tunnicliffe, a University of Victoria marine biologist who was not directly involved in the research, told CBC in an email. "All are beautifully adapted to their natural settings."
'All the characteristics of a sneeze'
Belinda is a tennis-ball sized sea sponge of the species Suberites concinnus who lives on the sea floor, about 23 metres below the surface of the water, off the coast of Vancouver Island.
Leys says the team gave the sponge a name to make it easier to distinguish between their Belinda-focused research and their studies of the species as a whole.
It's meant to be a feminine play on the cartoon character SpongeBob SquarePants, Leys says, though sea sponges are neither male nor female.
The team collected hundreds of hours of video of Belinda between 2012 and 2015, then spent the next decade analyzing the massive trove of data — a process that sped up in recent years with advances in machine learning.
They learned Belinda has both a daily and an annual routine, changing shape, size and colour with changing seasons. Rarely lonely, Belinda receives visitors from a diverse array of ocean critters, including snails, crabs, sea stars and anemones.
Belinda also "sneezes." Or, more precisely, the sponge contracts its entire body to clear plankton and other debris that builds up during filter feeding.
"It has all the characteristics of a sneeze," Leys said. "It sort of builds up. And then, eventually, it does one full contraction where everything goes out, and then it kind of relaxes again until the next one."
Sponges don't have muscle fibres, but instead use biochemical pumps to squeeze or expand their skin.
All sea sponges, Leys says, do this. But Belinda, it turns out, sneezes all day, every day, all summer long.
"A little sponge, it takes a very short time to sneeze. Well, 10 minutes, 20 minutes. But this sponge, it takes about a day," Leys said. "It basically contracts every day during the daytime hours, and so that's its summer routine."
Belinda vs. the blob
Come winter, however, Belinda takes it easy. It contracts to half its size, and its sneezes take months, rather than hours.
"It basically does nothing. It sits there completely quiet. You know, it's slightly twitching around," Leys said. " I wasn't expecting that at all."
The researchers posit Belinda enters a dormant state in the winter because there's less food — namely phytoplankton and zooplankton — to hoover up.
In fact, Belinda continually proved resilient against the changes happening around it.
It survived "the blob," an unusually warm mass of sea water that spread through the Pacific Ocean between 2013 and 2014, disrupting ecosystems and killing marine animals.
As the blob passed through, Belinda's colour slowly darkened from a pale yellow to deep orange, and it became lumpy. The sponge also got smaller, and its usually hearty contractions became "sluggish."
But, ultimately, Belinda bounced back to its usual, pale and perky self.
"Our study reveals how responsive and dynamic sponges are in their natural habitats," Dominica Harrison, lead author and University of Victoria graduate student, said in a press release from Ocean Networks Canada, the university's ocean observation facility.
"But beyond that, these data are helping us explore how environmental changes tied to climate change might impact the vital ecosystem functions that sponges provide."
When Merlin Best, a marine biologist with Fisheries and Oceans Canada, studies sea sponges, it's usually to learn more about how they form and contribute to the habitat around them, filtering water and providing the skeletal remains that form coral.
"Most of the time we think of sponges as these passive lumps on the sea floor, if we think about them at all," Best told CBC an email. "But it's very cool to see how dynamic they are if you watch them on their own timeline."
Belinda, Leys said, makes for a surprisingly great viewing experience.
"Watching the life around you in a different time frame, it's very soothing because it takes you out of your own world and it makes you realize there are other worlds going on beside yours," she said.
"That's a very comforting thought."
With files from Canadian Press. Interview with Sally Leys produced by Leslie Amminson
