Scaly Rock Crab

There are key differences in morphology and mitochondrial DNA that distinguish the scaly rock crab from other crab species it is closely related to. The crabs sometimes get mistaken for the Sally-Light-Foot crab (Gapsus albolineatus). The first morphologic difference occurs in the first zoeal stage in development. There is a distinct shape of the labe from the coaxial joints of the walking legs. They have a body width of five to six centimeters across. Their oval body is convex and covered with small bumps giving it their distinctive "scales". The pincers tend to be short and slender with long walking legs that are fringed with short hairs tipped with pointy claws. Mitochondrial DNA shows a clear genetic difference between P. squamosa and other species closely related to it. The crabs tend to have a large mixture of colors: shades of brown, blue, purple, and orange.

P. squamosa consumes mostly plant material and some small amphipods within a relatively full digestive tract. The Scaly Rock Crab tends to occupy the intertidal and oceanic zones throughout the Pacific region. The crabs tend to be held to the Indo-Pacific waters. Though known as rafting crabs, the Scaly Rock Crab is normally found on rocky shores when not rafting on an organism or object in open waters.