Pilumnidae

Pilumnidae is a family of brachyuran crabs, commonly known as hairy crabs. These crabs are characterized by the presence of dense setae or hairs covering their carapace and appendages, giving them a distinctly fuzzy appearance. The family includes a diverse range of species found in various marine habitats worldwide, with a notable concentration in the Indo-Pacific region.

Members of Pilumnidae inhabit a wide array of environments, from shallow intertidal zones and rocky shores to deeper offshore waters. They are often found associated with coral reefs, seagrass beds, and soft-sediment substrates. Their cryptic coloration and hairy covering provide effective camouflage against their surroundings, aiding in predator avoidance and ambush predation.

The diet of pilumnid crabs varies depending on the species and their habitat. Many are omnivores, feeding on algae, detritus, small invertebrates, and carrion. Some species are more specialized predators, while others are scavengers.

Reproduction in Pilumnidae follows the typical pattern for brachyuran crabs, involving direct fertilization and the brooding of eggs by the female. The larval stages are planktonic, dispersing before settling to the benthos as juvenile crabs. Due to their often small size and cryptic nature, many species are not well-studied, and their ecological roles are still being elucidated. Despite their common name, not all species within the family are conspicuously hairy.