Violet Vinegar Crab

The genus Episesarma comprises some of the largest sesarmid crabs. E. versicolor is distinguished by its white tipped violet chela (claw). Males grow up to a maximum length of 5 cm. The carapace is square-shaped and relatively flat, colored brown to brownish grey. The first gonopod of male E. versicolor has a narrower, shorter tip compared to other members of the genus. The dorsal portion of the dactylus possess 65-80 densely packed projections called tubercles These bony spine-like structures are more pronounced in males and, as seen in other crab species with tubercles, seem to be stridulatory organs for generating sound.

A mangrove inhabitant, it is found all over Southeast Asian countries such as Southern China, Hong Kong, Indonesia, Malaysia, Philippines, Singapore, Thailand, northern Australia and South Asian countries like Bangladesh, India and Sri Lanka. They also seem to possess an estimate of around 40 bony spine-like structures called tubercles. These are more pronounced in males and these tubercles like in other crab species that have them seemingly represent stridulatory organs used to create sound.

Episesarma versicolor are omnivorous, but feed primarily on calyx and leaves of water plants, mangroves, and mangrove associates. At Segara Anakan Lagoon, Java, Indonesia, E. versicolor feed on various food sources including detritus, bark, leaves, and on roots, algae and animal matter to a lesser extent. Their diet adapts to the environment, which helps them survive when food sources are scarce or changing. When food is abundant, such as during a feeding experiment, they prefer leaves with a high amount of nitrogen compounds. They have been observed cutting leaf litter and bringing some fragments back to their burrows. To remove leaves from trees, they tear off a section of the leaf with their claws and feed on those small sections they tear off.

Like most crabs they possess both male and female sexes. A ritual is generally performed utilizing both olfactory and tactile cues followed by an indirect sperm transfer.

E. versicolor is an important part of commercial fisheries in Southeast Asia. They are harvested by hand and often pickled in vinegar and/or salt solutions to be eaten with rice or deep fried. Due to their popularity in Thailand, they are being overfished. 18,000 tons of sesarmid crabs like E. versicolor are harvested from mangrove habitats and are consumed by Thai people. 12,000 tons of crab harvested annually from the Thai mangroves cannot keep up with domestic demand. Hence, Thailand imports at least 6000 tons of sesarmid crabs from the neighboring countries of Myanmar and Cambodia.