Portunidae
Rafinesque, 1815
Swimming Crabs
Genus Guides
6Portunidae is a of true crabs distinguished by their swimming ability, conferred by flattened fifth pereiopods modified into paddles. The family includes economically significant such as the blue crab (*Callinectes sapidus*) and the velvet crab (*Necora puber*). Members are typically fast, aggressive with strong, sharp claws. Several species have become outside their native ranges, particularly in the Mediterranean Sea via Lessepsian through the Suez Canal.
Pronunciation
How to pronounce Portunidae: //pɔːrˈtjuːnɪdiː//
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Identification
Distinguished from other crab by the fifth pair of legs, which are flattened into broad, paddle-like structures adapted for swimming. The is generally broad and flattened. Claws are typically strong and sharp. These features collectively separate portunids from non-swimming crab families such as Cancridae (rock crabs) and Majidae (spider crabs), which lack paddle-shaped rear legs.
Images
Habitat
Marine and estuarine environments; includes intertidal zones, shallow coastal waters, and continental shelf . Some occur in deeper waters. have established in the Mediterranean Sea, including the Ionian Sea off Italy.
Distribution
Worldwide in temperate and tropical seas. Greatest occurs in the Pacific and Indian Oceans. Native Atlantic distribution includes eastern and western Atlantic basins. documented in the Mediterranean Sea (northern Tunisia, Ionian Sea, Sicily). Records from Brazil (Sergipe) fill distribution gaps in South America.
Ecological Role
Predatory crabs that function as active hunters in benthic and pelagic environments. portunid may compete with native decapod crustaceans and alter local dynamics. Potential implications for fisheries through competition or as bycatch.
Human Relevance
Several support significant commercial and recreational fisheries, notably *Callinectes sapidus* (blue crab) in North America. Ornamental trade in freshwater crabs occasionally includes misidentified specimens. portunids require monitoring for fisheries management and conservation.
Similar Taxa
- CancridaeRock crabs lack paddle-shaped fifth legs and are not adapted for swimming; typically more rounded.
- MajidaeSpider crabs have elongated legs and spiny without swimming adaptations; often camouflaged with epibionts.
Sources and further reading
- BugGuide
- Wikipedia
- GBIF taxonomy match
- iNaturalist taxon
- NCBI Taxonomy
- Catalogue of Life
- A new crab is settling in the Mediterranean: early evidence of establishment of a Lessepsian species in the Ionian Sea | Blog
- crab | Blog
- Molecular phylogenetic reassessment of eastern Atlantic Callinectes (Brachyura, Portunidae)
- Feeding ecology and behaviour of intertidal Portunid crabs (Portunidae: Brachyura) in Moreton Bay
- On the occurrence of three exotic decapods, Callinectes sapidus (Portunidae), Portunus segnis (Portunidae), and Trachysalambria palaestinensis (Penaeidae), in northern Tunisia, with updates on the distribution of the two invasive portunids in the Mediterranean Sea
- Crustacea, Decapoda, Portunidae, Callinectes sapidus Rathbun, 1896: new record and filling distribution gaps
- Reproductive biology ofMacropipus tuberculatus(Roux, 1830) (Brachyura: Portunidae) in the Northwestern Mediterranean
- REPRODUCTIVE BIOLOGY AND EVIDENCE FOR HARD-FEMALE MATING IN THE BRACHYURAN CRAB THALAMITA SIMA (PORTUNIDAE)