Scientists have made a grisly discovery: the first recorded instance of a tarantula eating a snake in the wild.

Leandro Malta Borges, a graduate student at Brazil’s Federal University of Santa Maria, stumbled across the macabre scene on October 23, 2015, while he and his colleagues were walking through a grassland in southern Brazil called Serra do Caverá. (Watch a giant spider drag a mouse.)

Underneath a rock, they found a foot-long specimen of Erythrolamprus almadensis, a non-venomous snake—but its front and middle regions had been ripped to shreds by a large species of tarantula called Grammostola quirogai.

As Borges looked on, the tarantula huddled over the decomposing snake, chowing down on the exposed, liquefied guts.

In their description of the scene, published in Herpetology Notes in December 2016, the researchers chalk up the snake’s demise to an accidental break-in. In Serra do Caverá, many tarantula species, in particular sedentary females, hide in the rocks.

“Most likely, the snake was surprised upon entering the spider’s environment and hence [was] subdued by it,” the researchers write.

To kill the snake, the tarantula undoubtedly wielded its 0.8-inch-long fangs, but it's difficult to say what exactly caused the snake’s death.

Voracious Appetites

Scientists have known for decades that snakes can fall prey to tarantulas. In 1926, Brazilian researchers Vital Brazil and Jehan Vellard found that captive tarantulas occasionally ate snakes.

A 1992 study further reported that the Goliath birdeater tarantula (Theraphosa blondi) could eat fer-de-lance vipers, if nudged to do so. “They eat pretty much anything they can grab and overpower,” tarantula expert Chris Hamilton, a postdoctoral researcher at the Florida Museum of Natural History, says in an email.

World's Weirdest: World's Biggest Spider With a leg span nearly a foot wide, the Goliath birdeater tarantula is the world's biggest spider. And it has a special defense mechanism to keep predators from considering it as a meal.

“We also know that they eat frogs and lizards, and I’ve found them eating a small mouse.”

But Borges and his colleagues note that their observation is unique, since saw tarantulas eating snakes in the wild. “It is very gratifying to contribute to this record, since, as far as we know, there are only cases documented from situations in captivity,” says Borges in an email. (Watch a freshly eaten snake make an amazing escape.)

The researchers were extremely lucky: Most likely, snakes probably don’t end up on tarantulas’ menus all that often.

“One reason I think that we don’t see this very often is that it’s just rare,” says Hamilton, who wasn’t involved with the study.