[3] The genus Armases is defined by a primarily equatorial smooth carapace, which can be either slightly wider than long or vice versa.

[2] Armases can be distinguished from members of other genera such as Sesarma or Sarmatium by the way its carapace has laterally parallel margins on each side of its body.

[4]Armases is a useful species for studying trophic dynamics in coastal habitats due to their high local abundance in both saltmarsh and mangrove habitats (with a distribution ranging in elevation from subtidal to supratidal), and wide-ranging mobility that spans the mangrove/upland ecotone[5] Sexual dimorphism is evident in the species, as males are typically slightly larger and have a more prominent palm.

Due to the high population density in coastal environments wharf crabs can be used as indicators of habitat conditions.

[6] While the wharf crab is often deemed a detritivore, it is highly omnivorous and will supplement a detritus diet with microscopic insects and invertebrates.

[8] In mangrove habitats wharf crabs are a key component as omnivores in the food chain, they serve as carnivores, herbivores, and detritivores.

Consequently, this diverse diet also allows the species to live at relatively high population densities across a large margin of coastal ecosystems.

[11] The next time the crab molts it will become a juvenile version of its adult form and its larval life stages will be complete.