Nov. 1, 2017 - Coconut crabs are the largest land invertebrates, reaching sizes of over 3 feet in leg span and a weight of up to 9 lbs. Along with eating their namesake, coconuts, the crabs have been observed catching bigger prey like rats and birds, as well as fruits and nuts. Their presence on small islands may have a great effect on the nesting behavior of birds. Islands that contain coconut crabs have been observed with little to no bird populations.