Placetron

Lore & Background

The scaled crab derives its name from the scale-like pattern that covers its legs and partially covers its carapace. Its carapace is wide and trapezoidal, narrowing at the anterior end, and its chelae are spoon-like and largely covered in setae. Coloration ranges from clouded green to reddish, sometimes with banding along the legs. The abdomen is soft and leathery; females have abdomens covered in plates, while males have vestigial plates that give a rubbery look and feel.

Placetron wosnessenskii is found in waters from the Pribilof Islands to Puget Sound, typically at depths up to 110 m but also in shallow intertidal areas. As a lithode crab, it has an asymmetrical body. Its diet includes brittle stars, and it is preyed upon by sea otters and presumably other large predators. Many individuals have been observed in a symbiotic relationship with certain sea anemones, particularly Metridium senile and Metridium farcimen.

Reader's Guide

Placetron is significant as a monotypic genus within the king crabs, distinguished by its unique scale-like ornamentation and spoon-like chelae. Its single species, the scaled crab, occupies a specific niche along the North American west coast, from the Pribilof Islands to Puget Sound. The crab's biology reflects adaptations common to lithode crabs, including an asymmetrical body and a soft, leathery abdomen with sexual dimorphism in plate coverage. Its observed diet of brittle stars and its role as prey for sea otters place it within a broader coastal food web. The symbiotic relationship with sea anemones such as Metridium senile and Metridium farcimen adds ecological interest, suggesting a mutualistic or commensal association. The scaled crab's presence in both subtidal and intertidal zones indicates a degree of habitat flexibility. While few prey species have been directly observed, its feeding habits are assumed to resemble those of similar crabs. The genus remains notable for its morphological distinctiveness and its limited but well-defined geographic and depth range.

Did You Know?

• Placetron wosnessenskii is the only species in the genus Placetron.
• The crab's name comes from the scale-like pattern on its legs and carapace.