The Coconut Crab (Birgus latro)
Updated: Oct 13, 2021
The Coconut crab is the largest terrestrial crab in the world! They can weigh up to 9lbs and can get over 3ft long. They live on a number of Pacific Islands and coasts and are commonly seen knocking coconuts down from trees from which they feed on later.
A coconut crab is actually a large type of hermit crab. They come in a variety of beautiful colors and are quite mobile. They are known for climbing trees and knocking down coconuts. This is believed by some to be an indication of planning; and thus, intelligence, but German biologist, Holger Rumpf, who first scientifically documented many of the behaviors he witnessed, states that the climbing behavior is for cooling down and avoiding predators. While in the tree, the crab tries to get the coconut and knocks it down by accident.
It was believed for a long time that coconut crabs were opportunistic feeders but mostly vegetarian. They gained the name, robber crab, as they take strange items and food from people's homes. They were also found knocking over trash cans and digging through the trash for morsels, gaining another name of garbage or trash can crab.
In their natural environment, they specialize in eating fruits and nuts; however, the opportunist designation may have been inaptly assigned. Multiple eye witness reports have seen them eating rats, baby turtles, other crabs, kittens, and puppies. It was argued that perhaps the crab stumbled upon their remains. This does occur, but now, it is considered that these crabs may be hunters after all as one was caught stalking and eventually killing a sleeping sea bird.
Scary Fact: Their claw gripping pressure is equivalent to a lion's bite. Ouch!
The male seeks out the female and a battle ensues. If the male succeeds in flipping the female over, he mounts her and passes his spermatophore to her. The female places the fertilized eggs on her underside and when the time is right, she releases them into the ocean. As the baby crabs develop, they have gills and can breathe underwater, but lose this ability as they grow older and move onto land. That said, they must keep their special breathing organs (their ‘lungs’) a little moist in order to breathe properly. If they dry up, the crab will suffocate and die. On the flip side, they will die if tossed into the ocean as adults. Yes, they drown.
Habitat and Location
They are a pacific organism residing from the coastal islands of East Africa, extending across the Indian Ocean, all the way east to Hawaii. Interestingly, their habitat coincides with the coconut palm species, revealing a kind of co-evolution.
Can I eat them?
Someone always asks. Yes, coconut crabs are eaten by some people and are considered a delicacy though its taste is apparently something to be acquired and is not heavily desired.
They are apparently quite fast on land as well. See the video below to see just how fast these guys can move. Not quite as scary as the Garthim from the Dark Crystal, but close enough.