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The mangrove tree crab, Aratus pisonii, is common in the Indian River Lagoon.  Its carapace reaches approximately 1.5 inches in width, with body color being an olive green to brown.  The carapace is often mottled with brighter yellow or cream colored markings.  Eyes are widespread, placed in the far forward corners of the carapace.  Characteristic tufts of coarse black hair cover the chelae. The legs have sharp tips at the end to allow crabs to climb and cling onto trees and other structures.

Aratus pisonii are most commonly observed on red mangrove trees, but may be found on other structures such as docks and pilings.  When threatened, they quickly flee to water.

Similar Species:
Mangrove tree crabs are similar in overall body form to the spotted mangrove crab Goniopsis cruentata.  However, spotted mangrove crabs grow larger, up to3 inches, have a dark brown carapace and red legs.  In the spotted mangrove crab, the palms of the claws are white, and lack the dark tufts of hair present in Aratus pisonii

Mangrove tree crabs range from Florida to Brazil, including the Caribbean.  They are common in the Indian River Lagoon. 


Mangrove tree crab, Aratus pisonii. Photo courtesy of D. Elliot. 
Mangrove tree crab eating a beetle (Chalcolepidius sp.) larva.  Photo courtesy of C. Feller, Smithsonian Environmental Research Center.

Mangrove tree crabs eat mangrove leaves and propagules, but also feed opportunistically on insects and larvae in the tree canopy.