Anomuran
Guides
Petrolisthes eriomerus
flattop crab
Petrolisthes eriomerus, commonly called the flattop crab, is a small porcelain crab inhabiting the eastern Pacific coast of North America. It reaches 20 mm in carapace width and exhibits a distinctly flattened, rounded body form adapted for life under rocks and in crevices. The species employs filter feeding and deposit sweeping to consume diatoms and organic material. It displays notable social behavior, including aggregations and ritualized agonistic interactions between individuals.
Pleuroncodes
red crab, tuna crab, squat lobster, múnida
Pleuroncodes is a genus of anomuran crustaceans (squat lobsters) in the family Munididae, found in the eastern Pacific Ocean. Species occupy both pelagic and benthic habitats depending on life stage, with larvae and small individuals in pelagic waters and larger adults on the seafloor. The genus includes commercially and ecologically important species that form dense aggregations and serve as prey for large marine predators.
Pleuroncodes planipes
pelagic red crab, tuna crab, squat lobster, langostilla, benthic anomuran red crab
Pleuroncodes planipes is a pelagic and benthic anomuran red crab distributed across the eastern Pacific Ocean, from California to Panama. The species exhibits a complex life cycle with both pelagic and benthic phases: larvae and small individuals occupy open waters, while larger adults become exclusively benthic. It forms exceptionally dense aggregations on seamounts, with recorded densities up to 78 crabs/m² at depths of 355–385 m. The species tolerates hypoxic conditions (0.04 ml/l oxygen) and serves as a major prey item for large pelagic predators including yellowfin and skipjack tuna.