A mangrove tree crab. Image from wikimedia commons and used under the creative commons license.  Taken by Ianaré Sévi

Life History

            The mangrove tree crab has a life cycle that includes a larval stage and the adult form (Cuesta et al. 2005).  The larval period is about a month long and divided into four stages of zoea that are 4 to 6 days in duration each and a final megalopa stage that looks similar to the adult (Cuesta et al. 2005, Warner 1967).  Larval form of the mangrove tree crab is very vulnerable to predation by small fish.  During this time, the vast majority of mortality occurs (Warner 1967).

            The carapace length in the first stage of zoea is about 0.3 mm, and it will grow to about 0.47 mm in the final zoea and 0.69 mm in the megalopa (Cuesta et al. 2005).  The mangrove tree crab will reach maturity when its carapace width is about 12 mm.  At this point, the crabs begin reproduction (Warner 1967).  They grow through molting cycles when they shed their exoskeleton and the new one begins to harden.  The process takes several days.  Mature females usually reproduce once or twice between molting.  When a carapace width of about 12 mm is reached, the amount of energy used in reproduction causes the growth of female mangrove tree crabs to slow down compared to the growth of males.  Before this, they grow at the same rate (Warner 1967). 

            Mature mangrove tree crabs will mate and reproduce year-round.  Their breeding cycles were connected to moon phases with eggs most commonly hatching during full moons and new moons (Cuesta et al. 2005, Warner 1967).  This is not a very common trait in crustaceans.  It’s possible that it is related to changes in the tide that give Mangrove tree crabs a possible advantage. (Warner 1967).

Aratus pisonii used with permission from Gary R McClellan

            Mangrove tree crabs will copulate with males on top.  The male holds on to the females with its legs and puts its pleopod up to the female’s genitalia (Warner, 1967).   Once developed, the eggs remain attached to the female, and it will be fourteen to sixteen days until they are hatched (Cuesta et al. 2005, Warner, 1967).

           The eggs are spherical with a diameter of about 600 µm.  The embryo can first be seen on the fourth day of development.  By the tenth day the heart of the embryo is already beating.  On day fourteen, the yolk is almost completely gone, and it is ready to hatch (García-Guerrero and Hendrickx 2004).  When the eggs are to begin hatching, the females will move out to the edge of the swamp and down into the water.  They will then shake in order to disperse the hatching larvae.  They will do this for a minute or two until all the eggs have hatched. (Warner 1967).

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