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Why do dead whales explode?

Why do dead whales explode?


The processes going on inside the carcass in Newfoundland are actually pretty typical

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A beached blue whale in Kuwait earlier this year
A beached blue whale in Kuwait earlier this year
Getty Images

A dead blue whale washed up on the shore of an eastern Canadian town several weeks ago, and has been causing quite a stir ever since. Locals tell the media they're worried the bloated, smelly carcass will explode, and what's worse is that their fears aren't unfounded, as "whale explosions" have happened before. But the most interesting part of this story isn't that this rare event is taking place before our eyes, but rather that we don't hear about potentially explosive dead marine mammals more often. After all, the decomposition stages that this carcass is currently demonstrating are pretty typical.

"release is sometimes slow, and sometimes catastrophic."

"Pressure release is sometimes slow, and sometimes catastrophic," says Bruce Mate, director of the marine biology institute at Oregon State University. Mate has dealt with a lot of dead whales throughout his career, so he's also seen his fair share of bloated remains. "The gas buildup is just a normal part of the degradation of tissue." That's why he isn't all that worried about the whale that washed up on the beach at Trout River, in Newfoundland. "Dead animals buoy up to the surface all the time, and they float there until the pressure is released through some weak point," he says. The weak points are often ones that are already in place, such as a whale's mouth or anus. But hungry sharks can also contribute to the creation of these sorts of weak points.

But why does gas build up in these whales in the first place? Wolfgang Weinmann, a forensic toxicologist at the University of Bern in Switzerland, explained in an email to The Verge that the gases that build up in dead animals "come from different sources." In this situation, he said, putrefaction and fermentation are likely the culprits. During putrefaction the proteins in an animal's tissues break down. This produces a number of "stinky gases," Weinmann wrote, in addition to methane. It's also what causes organ liquefaction. Fermentation, on the other hand, is the process in which various tissues dry out. This produces a number of other gases, such as carbon dioxide. So when putrefaction and fermentation come together, you can sometimes end up with a spectacularly bloated carcass. And because whales have a thick layer of blubber beneath their skin, air trapped within stays mainly in the whale until its skin degrades — or until someone decides it's time to relieve all that pressure.

Spectacular because of its size

As for the impressive nature of these explosions, it really just has to do with size, Mate says. Because decomposition is taking place in such a large animal, more gas and pressure can build up inside its remains. "You don't get this type of exciting or dramatic response when you are looking at a squirrel roadkill or a raccoon along the road," he says. "But the same process is going on in the squirrel, it's just at a much smaller scale." And make no mistake, Mate says, the pressure building up inside this animal "will release itself eventually" — it just might not be the sort of explosion we're imagining. Slow deflations, he says, work just as well.

Even so, the town should hire a boat to drag the carcasses out to sea, just in case, Mate says. Once sufficiently far away from the town, someone can perform a controlled release of the whales' internal pressure by making a shallow slit with a long-handled knife. "In my experience," he says, "you don't have to go down all the way to where the pressure is — just create a weakness and walk away."

organs "propelled out 30, 50 feet."

But Mate admits that even a controlled release can be botched. If someone were to go in too deep, then the release could be "catastrophic," he says. "There have been people who have stood on top of these animals and have been blown into the air." When this happens, a whale's internal organs are "sometimes propelled out 30, 50 feet." If the release is done correctly, however, the carcass would slowly deflate and sink to the bottom, providing tons of food to the animals below.

Unfortunately, this idea probably won't sit well with some of the town's inhabitants, as many are hoping to preserve and exhibit the whale skeleton as a tourist attraction. This could still happen, but an announcement from the Royal Ontario Museum yesterday, in which the Museum said it would send researchers to recover two of the nine whale carcasses that have recently washed up in the area, might foil these plans. Already, locals have expressed displeasure with the idea of parting with the bloated blue whale. "It's not going to be no small feat to move this to Ontario," Jenny Parsons, a restaurant operator in Trout River, told CBC Radio's As It Happens. Ideally, Parsons would like to see the whale removed from the community while it decomposes, and then returned once the skeleton is clean. That, she said, makes more sense than moving the whole thing to Toronto.

Mate thinks keeping the skeleton is feasible — he has done just that several times — but also says that making that happen is expensive and complicated. The team that will prepare the skeleton will need to remove all the soft tissue, meaning about 85 percent of the whale's mass. Then, they'll have to figure out how to dispose of the flesh, which won't be easy. "You don't just put something like that casually in the back of your pickup, and drive it out to some rural area," he says. But if they really want to keep the skeleton, they can — "it's just a really big project."