Cancridae

Distinguished from other crab families by a combination of broad, oval to rounded carapace shape; well-developed walking legs with setose or hairy surfaces in some species; and chelipeds of moderate to large size. The family historically centered on the genus Cancer, but current taxonomy recognizes separate genera (Anatolikos, Cancer, Glebocarcinus, Metacarcinus, Platepistoma, Romaleon) based on morphological and fossil evidence. Specific identification requires examination of carapace margin structure, anterolateral teeth, and male abdominal appendages.

Marine benthic environments ranging from intertidal zones to depths exceeding 375 m. Substrates include muddy bottoms, rocky subtidal habitats, and mixed sediments. Species occupy temperate coastal waters in both Northern and Southern Hemispheres, with some populations spanning biogeographic transition zones including upwelling systems.

Global distribution concentrated in temperate waters. Northern Hemisphere: North Pacific and North Atlantic. Southern Hemisphere: Eastern Pacific from Peru to southern Chile (6.9°S to 42°S), with some species extending to Ecuador. European records include Denmark, Norway, and Sweden.

Carnivorous and opportunistic: other crustaceans, bivalves, and gastropods (documented for Romaleon setosum). Specific dietary composition varies by species and habitat.

Complex life cycle with planktonic larval dispersal. Larval development includes multiple zoea stages; planktonic larval duration exceeds two months in some species (55–84 days documented in congenerics). Sexual maturity reached at 2–3 years. High fecundity: 288,750–740,920 eggs per female in Cancer porteri, varying with female size. Reproductive timing varies latitudinally, with multiple annual cycles in northern populations shifting to single annual cycles in southern populations.

Long-distance larval dispersal facilitated by extended planktonic duration and strong offshore advection capacity. Adults are benthic predators. Some species exhibit population genetic homogeneity across thousands of kilometers despite environmental heterogeneity and fishery exploitation.

Significant benthic predators in subtidal environments, particularly in the Humboldt Current system. Prey for coastal fishes (Paralabrax humeralis, Pinguipes chilensis) and cephalopods (Robsonella fontaniana). Commercially important: Cancer porteri constitutes 17% of Chilean brachyuran landings; Romaleon setosum is one of the most important predators in northern and central Chilean subtidal zones. Bycatch component in demersal crustacean fisheries.

Supports commercial and artisanal fisheries in multiple regions. Chilean fisheries for Cancer porteri and Romaleon setosum are regulated with minimum catch sizes (12 cm for R. setosum) and seasonal protections for egg-bearing females. Management informed by population genetic studies showing extensive gene flow and single-stock structure.

• PortunidaeSwimming crabs with flattened, paddle-shaped fifth pereiopods adapted for swimming; Cancridae lack swimming paddles and have more robust walking legs.
• MajidaeSpider crabs with extremely long, slender legs and often triangular or elongated carapaces; Cancridae have shorter, stouter legs and broad, oval carapaces.
• GeryonidaeDeep-sea crabs with similar body form but distinct gonopod morphology and typically greater depth ranges; taxonomic separation based on male reproductive structures and larval development mode.

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• High gene flow and lack of genetic structure in the commercially important crab Cancer porteri (Brachyura: Cancridae) along 1,500 km of the Chilean coast revealed by SNP markers.
• Population homogeneity with unequal exploitation and recruitment contribution within the 2700 km geographic distribution of the commercial hairy crab Romaleon setosum (Decapoda: Cancridae) in Chile.