Interactions
The majority of the mangrove tree crab’s diet is plant material. However, they are omnivores and will also feed on small invertebrates if given the chance (Beever et al. 1979, Erickson et al. 2008). The larvae of mangrove tree crabs will typically live on diatoms and zooplankton (Schwamborn et al. 2005). The most common food source for the mangrove tree crab is Rhizophora mangle or the red mangrove. Mangrove tree crabs will also feed on the leave of black mangroves and white mangroves (Beever et al. 1979).
The mangrove
tree crab will usually be found living on the tree it uses for a
food source. It will consume part of the leaf by scraping the
surface of it and leaving behind damage (Beever et al. 1979).
In instances where mangrove swamps have been destroyed, mangrove
tree crabs can be found on pilings in the water. These crabs
survive on other foods such as algae that also are found on the
pilings and do not have access to mangrove trees (Beever et al.
1979). Mangrove tree crabs will also prey on small arthropods
when it can manage to catch one. It will use this as a
supplement for its main food of red mangrove leaves (Beever et al.
1979, Erickson et al. 2009, Erickson et. al. 2008). Beever et
al. (1979) observed that mangrove tree crabs that were accustomed to
eating a specific food source, could not survive with a different
food source that other mangrove tree crabs could survive on.
Crabs that ate algae were not able to live on leave of the red
mangrove (Beever et al. 1979).
The mangrove
tree crab is also an important food source to many organisms.
The larvae are preyed upon very heavily by small fish in mangrove
environments. The chances that a mangrove tree crab will
survive to an adult are incredible slim (Beever et al. 1979, Warner
1967). The large mangrove crabs or Goniopsis cruentata
depend
on mangrove tree crabs as a food source. The large mangrove
crab will aggressively jump on any chance to grab a mangrove tree
crab that has fallen from a tree. Fish such as the mangrove
snapper or Lutjanus griseus will eat adult mangrove tree crabs that
have fallen into the water. The white ibis or Eudicimus albus
is another predator of the mangrove tree crab. It will grab
them if it sees the crab exposed (Beever et al. 1979, Warner 1967).
While
researching this topic, I did not find any example of a parasitic
relationship involving the mangrove tree crab as either a host of a
parasite. I also did not find any example of these crabs being
eaten or used by humans.