C. sapidus is of considerable culinary and economic importance in the United States, particularly in Louisiana, the Carolinas, the Chesapeake Bay, Delaware, and New Jersey.

Unlike the other fisheries affected by climate change, blue crab is expected to do well; warming causes better breeding conditions, more survivable winters, and a greater range of habitable areas on the Atlantic coast.

The genus Callinectes is distinguished from other portunid crabs by the lack of an internal cartilaginous spine on the carpus (the middle segment of the claw), as well as by the T-shape of the male abdomen.

A popular mnemonic is that the male's apron is shaped like the Washington Monument, while the mature female's resembles the dome of the United States Capitol.

[14]: 491 C. sapidus is native to the western edge of the Atlantic Ocean from Cape Cod to Argentina and around the entire coast of the Gulf of Mexico.

[15][16] It has recently been reported north of Cape Cod in the Gulf of Maine, potentially representing a range expansion due to climate change.

[19] In some parts of its introduced range, C. sapidus has become the subject of crab fishery, including in Greece, where the local population may be decreasing as a result of overfishing.

[21] Some of the natural predators of C. sapidus include eels, drum, striped bass, spot, trout, some sharks, humans, cownose rays, and whiptail stingrays.

It typically consumes thin-shelled bivalves (such as clams, mussels, and oysters), crustaceans, annelids, small fish, plants (such as eelgrass), and nearly any other item it can find, including carrion, other C. sapidus individuals, and animal waste.

[29] The most harmful parasites may be the microsporidian Ameson michaelis, the amoeba Paramoeba perniciosa and the dinoflagellate Hematodinium perezi, which causes "bitter crab disease".

[30] In 2021, scientists from the University of Maryland completed DNA sequencing on C. sapidus's genome in Baltimore after six years of research to help better understand the species.

[31] This genetic map is expected to help scientists understand how the blue crabs will be affected by climate change and warmer water temperatures, along with which mutations cause disease, traits that influence meat production, and which females have the best reproductive ability.

[7] During seven planktonic (zoeal) stages, blue crab larvae float near the surface and feed on microorganisms they encounter.

Chemical cues in estuarine water prompt metamorphosis to the juvenile phase, after which blue crabs appear similar to the adult form.

To ensure that a male can mate, he actively seeks a receptive female and guards her for up to seven days until she molts, when insemination occurs.

Females migrate to the mouth of the estuary to release the larvae, the timing of which is believed to be influenced by light, tide, and lunar cycles.

[40] As early as the 1600s, the blue crab was an important food item for Native Americans and English settlers in the Chesapeake Bay area.

In the lower Chesapeake Bay, crabs were even considered a nuisance species because they frequently clogged the nets of seine fishermen.

For example, after observing a slight decline in harvest, the fishing commissions of Virginia and Maryland put size limits into place by 1912 and 1917, respectively.

Blue crab spoiled quickly, which limited distribution and hindered the growth of the fishery for several decades.

Other plants opened soon after, although commercial processing of hard blue crabs was not widespread until World War II.

[34] The industry was not commercialized for interstate commerce until the 1990s, when supply markedly decreased in Maryland due to problems (see above) in Chesapeake Bay.

[45] This tendency may have made it difficult for managers to predict the severe decline of the Chesapeake's blue crab populations.

Once considered an overwhelmingly abundant annoyance, the declining blue crab population is now the subject of anxiety among fishermen and managers.

[46] Many factors are to blame for low blue crab numbers, including high fishing pressure, environmental degradation, and disease prevalence.

The trotline, a long baited twine set in waters 5–15 feet deep, was the first major gear type used commercially to target hard crabs.

The blue crab and diamondback terrapin have overlapping ranges along the East and Gulf Coasts of the United States.

To reduce terrapin entrapment, bycatch reduction devices (BRDs) may be installed on each of the funnels in a crab pot.

[50] BRDs effectively reduce bycatch (and subsequently mortality) of small terrapins without affecting blue crab catch.

[55] The blue crab is the namesake of the Jersey Shore BlueClaws team in minor-league baseball playing in the South Atlantic League.