The world’s most dangerous fart - Nick Caruso and Dani Rabaiotti

For most humans, farts are a welcome relief, an embarrassing incident, or an opportunity for a gas-based gag. But for many other creatures, farts are no laughing matter. Deep in the bowels of the animal kingdom, farts can serve as tools of intimidation, acts of self-defense, and even weapons of malodorous murder.

The smelliest parts in the animal kingdom aren’t lethal, but they might ruin your trip to the beach. Seals and sea lions are well-known for having truly foul farts due to their diet. Fish and shellfish are incredibly high in sulfur. And during digestion, mammalian gut bacteria breaks down sulfur and amino acids containing sulfur to produce hydrogen disulphide, a gas with a smell resembling rotten eggs.

Seals and sea lions can’t help their funky flatulence, but some animals deploy their farts strategically. Both the Eastern hognose snake and the Sonoran coral snake use a tactic called cloacal popping. This involves sucking air into their cloaca— a hole used for urinating, defecating and reproduction— and then shooting it back out with a loud pop. These pops are no more dangerous than a sea lion’s stench, but they are effective at scaring off would-be predators.

Meanwhile, the flatulence of beaded lacewing larvae are silent and deadly. Their farts contain a class of chemical known as allomone that has evolved specifically to paralyze termites. In fact, this allomone is so powerful, a single fart can immobilize multiple termites for up to three hours, or even kill them outright. Either way, these toxic farts give beaded lacewing larvae plenty of time to devour prey up to three times their size.

For some other animals, however, holding farts in can be deadly. The Bolson pupfish is a small freshwater fish found in northern Mexico. These fish feed on algae and other small organisms in the sediment. But during the hottest days of the summer, this algae produces a lot of gas. If a pupfish doesn’t fart this gas out, it becomes buoyant— making it easy prey for passing birds. And it isn't just predators they have to worry about.

Excessive gas buildup can actually burst their digestive systems. Researchers have found groups of several hundred dead pupfish that failed to fart for their lives. Fortunately for humanity, animal farts can’t directly harm a human— outside making us lose our lunch. But in the right circumstances, some animal flatulence can create surprisingly dangerous conditions.

In the fall of 2015, a tripped smoke alarm forced a plane to make an emergency landing. Upon further inspection, officials found that there was no fire— just the burps and farts of over 2,000 goats being transported in the cargo bay. The change in air pressure had caused them to pass gas en masse. Thankfully, this story of farting goats had relatively low costs.

But the most dangerous flatulence in the world may actually come from a similarly unassuming mammal: the humble cow. There are nearly one billion cows in the world, most of them raised specifically for milk and meat. Like goats, cows are ruminants, which means their stomachs have four chambers, allowing them to chew, digest and regurgitate their food multiple times.

This process helps them extract extra nutrients from their food, but it also produces a lot of gas. This is particularly troubling because one of the gases cows emit is methane, a major greenhouse gas that contributes heavily to global warming. One kilogram of methane traps dozens of times more heat in the atmosphere than one kilogram of carbon dioxide.

And with each cow releasing up to 100 kilograms of methane every year, these animals have become one of the biggest contributors toward climate change. So while other animals may have louder, fouler, or even more toxic farts, cow flatulence may be the most dangerous gas ever to pass.