Parasesarma pictum  

Subbranchial and subhepatic regions below the orbits of the eye covered with reticulated network of dense granules with short setae (= pterygostome). Carapace quadrilateral. Male chela with 2 transverse pectinate crests on propodus, inner surface of propodus with transverse vertical line of granules and differentiated smooth tubercles (13-17, usually 16) on dactylus. On male abdomen, telson much longer than broad at base.

Vernacular name: Japanese shore crab.

Like all members of the family Sesarmidae, these crabs have a reticulate pattern of setae on their faces which they use to recirculate water in their gill chambers so they can maximise the oxygen level in the water. This way, they can live in extreme mud habitats and areas where water is scarce. In addition, their claws and faces have special rows of granules known as stridulatory granules, which they can use to generate sound so that they can communicate between themselves. Each species has its own diagnostic pattern of granules.