The Spined-back Hairy Crab, scientifically known as Pilumnus sayi, is a fascinating crustacean species belonging to the family Pilumnidae. This crab is distinguished by its spiny carapace and hairy appendages, contributing to its unique appearance and name. It’s a relatively small crab species, reaching a maximum size of around 3 centimeters in width.
Description & Characteristics
The Pilumnus sayi exhibits a distinctive, somewhat flattened carapace with a prominent spine on its back, earning it the moniker “Spined-back”. As its name suggests, the crab’s body and appendages are covered in short, fine hairs. These hairs are thought to play a role in camouflage and sensory perception. The crab’s color ranges from a light brownish-gray to a darker reddish-brown, blending seamlessly with its surroundings.
Habitat and Occurrence
The Spined-back Hairy Crab, Pilumnus sayi, is typically found in shallow, coastal waters along the Atlantic coast of North America. It prefers habitats with a sandy or rocky bottom and ample vegetation. The species is particularly common in intertidal zones, where it can tolerate fluctuations in salinity and water temperature. Pilumnus sayi is often found in the neritic zone, which encompasses the shallow waters extending from the shoreline out to the edge of the continental shelf. Its ability to thrive in various environments makes it a resilient species, well-adapted to the dynamic coastal ecosystem.
Taxonomy
The Spined-back Hairy Crab, Pilumnus sayi, falls under the Class Malacostraca, which includes a wide range of crustaceans, and the Order Decapoda, encompassing crabs, lobsters, shrimp, and crayfish. It belongs to the family Pilumnidae, a family that includes a diverse group of crabs, many of which are characterized by their flattened carapaces and hairy appendages.
Feeding
Pilumnus sayi is a predatory crab, actively hunting small invertebrates such as worms, snails, and other crustaceans. Its sharp claws are used to capture and crush prey, while its hairy appendages aid in gathering food. This crab plays an important role in the marine food web, controlling populations of smaller organisms.
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