Feeding habits of non-ocypodid crabs from two mangrove forests in Kenya

Abstract

The stomachs of 194 crabs belonging to 11 species, commonly inhabiting mangrove areas, were collected in two Kenyan mangrove forests, in Gazi Bay and Mida Creek, and their contents were analyzed. Both the stomach fullness (a subjective estimation) and the composition (the plant:animal matter ratio) of the food ingested were recorded. Results show that few species are either strictly herbivorous (Sesarma ortmanni and Selatium elongatum) or strictly carnivorous (Eurycarcinus natalensis), while most of the species are non-specialized and normally eat a wide range of plant items, mangrove leaf litter and algae, and animal prey, mostly bivalves, gastropods, anomurans and other brachyurans. Crab stomachs with a higher percentage of mangrove leaf litter and algae were significantly fuller than those with animal items. Most of the crabs display an omnivore feeding habit and feed on a wide range of items. Among the Sesarminae, the most herbivorous group, the only species showing a significant degree of specialization is Sesarma leptosoma, which is able to reach the mangrove canopy to feed on fresh leaves.