Pilumnus fissifrons, commonly referred to as the “fissured-fronted crab,” is a species of crab belonging to the family Pilumnidae. It is a relatively small crab that is found in a variety of marine habitats, particularly in the Indo-Pacific region.
Description & Characteristics
Pilumnus fissifrons is characterized by its relatively small size, typically reaching a maximum carapace width of around 30 mm. The carapace is broadly oval in shape and is usually a mottled brown or reddish-brown color. One of the defining features of this species is its fissured frontal margin, giving it its common name. The “fissures” are essentially a series of shallow grooves that run along the front edge of the carapace.
Habitat and Occurrence
Pilumnus fissifrons is a common inhabitant of intertidal and shallow subtidal zones, primarily in rocky and sandy habitats. It can often be found among algae, coral rubble, and seagrass beds. The species is generally distributed throughout the Indo-Pacific region, including areas like the Red Sea, the Indian Ocean, and the western Pacific Ocean. It is a prominent inhabitant of the neritic zone, the marine zone that extends from the shoreline to the edge of the continental shelf.
Taxonomy
Pilumnus fissifrons is a member of the family Pilumnidae, which contains a diverse array of crabs commonly known as “mud crabs” or “sand crabs.” The Pilumnidae family is further classified under the order Decapoda, which includes all crabs, lobsters, shrimp, and other decapod crustaceans. Finally, the family belongs to the Class Malacostraca, a diverse class containing over 40,000 species of crustaceans.
Feeding
Pilumnus fissifrons is an omnivore and its diet primarily consists of small invertebrates, algae, and detritus. It is a scavenger and will readily consume a variety of food items that it finds in its habitat. The crab’s feeding behavior is often opportunistic, and it will take advantage of readily available food sources.
Image References