Coconut crabs, known in Indonesia as ketam kenari, are the world’s largest land crab. They’re also quite an unusual species: these invertebrates can live up to 60 years and measure a meter long (3 feet) from leg to leg, with claw strength 10 times greater than a human’s grip. While most photographs of these crabs show them during the day, coconut crabs are actually nocturnal, and despite their name, they don’t solely eat coconuts — although they’re capable of ripping them apart with their impressive claws.

Coconut crabs (Birgus latro) are widespread across the Pacific and Indian oceans, including in Indonesia, which straddles both. But a newly published conservation assessment finds they’re also edging closer to extinction. The species’ conservation status is now listed as “vulnerable” by the IUCN, the global conservation authority.

“We were getting reports of coconut crab populations either declining or being extirpated from areas,” said assessment co-author Neil Cumberlidge, chair of the Freshwater Crustacean Specialist Group at the IUCN and professor of biology at Northern Michigan University. “This was coming initially from the Pacific, but other people were chiming in and saying, ‘Yeah, I’ve noticed it where I am … in eastern Indonesia.’”