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Features of Natural Interest

Land crabs Johngarthia lagostoma are a near-endemic of Ascension Island, being found on just three other islands in the South Atlantic - Ilha Trindade, Fernando de Noronha and Atol das Rocas. Prior to human settlement, J. lagostoma was the main terrestrial omnivore on the island. The carapace of the land crab can exceed 10 cm in width and the leg span can reach approximately 25 cm. J. lagostoma exists in two distinct colour morphs, one yellow and one purple, with few intermediates. Although primarily nocturnal, the land crabs can be observed during the day in the high, moist areas of Green Mountain, often under vegetation where it is darker. They spend much of the day in burrows excavated in vegetated areas and pyroclastic deposits. They feed mainly on plant material, but will scavenge dead animals and occasionally catch live ones - it is probable that they consumed eggs and chicks of seabirds in the past when both species were more numerous on the mainland. Between January and May, many adults migrate from higher elevations to spawning sites along the southern and eastern shores - the majority of spawning occurs at North East Bay. 

Female land crab Johngarthia lagostoma.

© Ascension Island Government Conservation Department
(Features of Natural Interest, 26 of 32 - Slide ref. 618)