This article was created in partnership with the National Geographic Society.

On Saturday, the curators at a natural history museum in Davao City, the Philippines, got a call from the local marine agency: An emaciated-looking whale in the Davao Gulf was vomiting blood, listing badly as it swam, and was very likely going to die shortly. They should come pick up its body.

When Darrell Blatchley, a marine mammal expert and the curator at the D’Bone Collector Museum in Davao City, brought the whale back to the lab to open it up for a necropsy, he found something shocking: more than 88 pounds of plastic waste jammed into its belly.

“Plastic was just bursting out of its stomach,” he said. “We pulled out the first bag, then the second. By the time we hit 16 rice sacks—on top of the plastic bags, and the snack bags, and big tangles of nylon ropes, you're like—seriously?”

His son, who was attending the necropsy, said “Dad, how did it even live this long?”

The plastic trash was so densely packed into the dead whale's stomach that it felt as “hard and compacted as a baseball,” he said, only many times bigger—more like two dense basketballs of trash, about eight percent of the juvenile beaked whale's total weight. Some of it had been in the stomach so long it had started to calcify.

The curvier beaked whale, a young male about 15 feet long and weighing 1,100 pounds, likely died of starvation and dehydration brought on by the plastic stuffing its belly. Whales absorb water from the food they eat, and there was no sign that any food had made it into its intestines for many days. Its body was destroying itself from the inside: Its stomach acid, unable to break down the plastic waste, had worn holes through its stomach lining instead.

This whale was far from alone

As the plastic pollution crisis grows, more and more dolphins, whales, birds, and fish are found dead with their stomachs full of plastic. In 2015, scientists estimated that around 90 percent of all seabirds have ingested some amount of plastic; UNESCO estimates that 100,000 marine mammals die because of plastic pollution each year.

The cause of death varies. Sometimes, like in this case, plastic blocks food from traveling from stomach to intestine, essentially starving the animal. Other times, sharp edges poke holes in their internal organs.

In most cases, the amount of plastic animals ingest isn’t enough to kill them, says Matthew Savoca, a Stanford-based whale expert who also studies plastic pollution. But the effects can cascade, even if only a little bit of plastic lodges in their bellies, taking up valuable space. “If you’re eating 10 percent less calories than your neighbor, day after day, that adds up,” says Savoca.

“Basically, wherever we're looking for plastics, we're finding them,” says Savoca, “Now, we’re seeing that even in places humans never even have been close to, we find our trash. And not just that, but animals eating our trash.”

The waters around the Philippines are particularly treacherous for many marine animals. The country is one of the most prolific plastic polluters in the world, and many of its waterways are thick with trash.

The country has many laws in place that aim to curb plastic pollution, but enforcement has been light, and the logistics of managing waste disposal across the country’s more than 7,000 islands is challenging, and plastic-wrapped items are for sale nearly everywhere.

Blatchley has recovered 61 whales that died in the nearby Davao Gulf. Of those, he estimates that plastics were the cause of death for about 45 of them. The problem is exacerbated, he says, by heavy fishing in the region, which has limited the amount of food available for the whales to eat, making them even more likely to try to eat plastics floating nearby.

“It’s just tragic that this is becoming the norm, to expect that these whales will die because of plastic rather than from natural causes,” he says. “We’re losing them faster than they can evolve to learn not to eat the plastic.”