Pleuroncodes

Stimpson, 1860

red crab, tuna crab, squat lobster, múnida

Species Guides

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Pleuroncodes is a of anomuran crustaceans (squat lobsters) in the Munididae, found in the eastern Pacific Ocean. occupy both pelagic and benthic depending on life stage, with larvae and small individuals in pelagic waters and larger on the seafloor. The genus includes commercially and ecologically important species that form dense and serve as prey for large marine .

MBNMS - pelagic red crab (27230141934) by National Marine Sanctuaries. Used under a Public domain license.Pleuroncodes planipes uzun3 by William Roger Uzun. Used under a CC BY-SA 4.0 license.MBNMS - pelagic red crabs (27230142014) by National Marine Sanctuaries. Used under a Public domain license.

Pronunciation

How to pronounce Pleuroncodes: //plʊˈɹɒŋkoʊdiːz//

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Habitat

Benthic on seamounts, continental shelf, and continental slope; depths ranging from ~280 m to 385 m for high- . Associated with hypoxic conditions (oxygen levels as low as 0.04 ml/l) and dense turbid layers 4–10 m above the bottom. Pelagic waters for larval and small stages.

Distribution

Eastern Pacific Ocean: California Current system (including southern California Bight), western Baja California, and coastal eastern tropical Pacific (Hannibal Bank seamount off Panama). Range extends from temperate to tropical waters.

Diet

Pelagic stages: phytoplankton via specialized filtration feeding, plus small zooplankton. Benthic stages: deposit feeding and scavenging.

Life Cycle

Larvae and small individuals (<2.6 cm length) are pelagic; larger individuals transition to exclusively benthic existence. Breeding occurs in winter (primarily February–March in California Current). Pelagic ovigerous females and larvae have been observed over bathyal and abyssal depths (~2,000–3,500 m), indicating pelagic can occur. Late zoeae and megalopae are carried offshore by geostrophic currents.

Behavior

Forms high- benthic or swarms (up to 78 individuals/m²) with patchy distribution; density peaks in patch centers resembling insect swarm structure. Exhibits diel vertical in larval stages: near surface at night, deeper during day. Large pelagic patches historically reported spanning 7–10 km.

Ecological Role

Major prey item for large pelagic including yellowfin tuna and skipjack tuna. Contributes significantly to seamount and ecological hotspot dynamics. Spatial overlap with forage fish such as Peruvian anchovy in pelagic .

Human Relevance

Supports commercial fisheries and serves as for productivity. Mass strandings on beaches (e.g., San Diego 2015) attract public attention. Subject of acoustic survey methods for estimation in marine protected areas.

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