Coconut crabs are the largest land-dwelling invertebrates – they can grow up to one metre in height, and weigh up to four kilograms. That’s obviously much larger than the regular crab, and which also makes them somewhat more dangerous.

A disturbing video (above) recorded by coconut crab researcher Mark Laidre, of Dartmouth College, USA, shows the gigantic crab hunting and cruelly killing a seabird. It’s the first time that such behaviour – of actively hunting and killing a large, vertebrate animal – has been observed among coconut crabs.

The crab, according to Laidre, climbed a tree and attacked the seabird in its nest on a branch close to the ground. The predator broke the bird’s wing, causing it to fall out of its nest, and then sunk its deadly claws into its body. Coconut crabs get their name for their ability to break into and eat coconuts – so imagine the strength in those claws, which left the bird alive, but incapacitated.

The species was previously thought to be scavengers, but Laidre describes that things got “pretty gruesome” after other coconut crabs arrived and pulled the incapacitated bird apart. The incident took place in the remote Chagos Island in the Indian Ocean.