5 Things You Didn't Know About Blue Crab

Everything you ever wanted to know about blue crab—from what blue crabs eat to the shocking number of eggs female crabs release at once.

Blue crabs are one of the most recognizable varieties of shellfish. They’re small—mature males are only about nine inches wide—and their lifespan is rather short, just 3 years on average. Blues are also one of the most popular sources of food for many coastal communities. Here, learn a bit more about these colorful crustaceans.

Blue Crabs wait in a bin 21 March 2005, at the Maine Avenue Fish Market in Washington, DC.
PAUL J.RICHARDS / Staff / Getty Images

Their Scientific Name Suggests They’re Delicious

The blue crab’s scientific name is Callinectes sapidus, which translates to “savory beautiful swimmer.”

Indeed, their back legs, which are paddle shaped, make them excellent swimmers. And blue crabs are prized for their sweet, delicate flavor and tender meat. Blues are among the most heavily harvested creatures across the world, and typically fetch high prices in ports around the world.

Males and Females Look Different

While both sexes have sapphire-tinted claws, females have an additional display of color: red highlights on the tips of their pincers.

Likewise, flip a blue crab over, and you can spot the sex by taking a look at the crab’s “apron.” The apron is the folded surface of the belly, which comes in three distinct shapes: T-shaped on male abdomens, triangular on young females, and rounded and circular on older females.

Their Natural Habitat Is Large—and Expanding

These delightfully colorful crabs take up residence in waters from Nova Scotia to the Gulf of Mexico, and even further south along the coasts of Argentina and Uruguay. Nowhere is the crab more iconic, though, than the Chesapeake Bay. In the waters off Maryland and Virginia, the blue crab population thrives in the brackish estuaries and salt marshes.

Stowaway blue crabs on ship ballasts have even showed up in the Mediterranean. There, however, the crab is invasive. It was first seen off Egyptian waters in the 1940s, but reports of blue crab sightings in Italy, Israel, Greece, and Turkey have been made, too. As such, many coastal communities have found ways to use the foreign crustaceans as a source of food and income.

Females Mate Just Once

Blue crab mating season stretches from May to October. Once females reach sexual maturity, they mate with a male only once. (Males will mate with multiple females during their lifespan.)

Once the crabs mate, an egg mass develops beneath the female’s apron. This mass, or sponge, can contain as many as 2 million eggs. Eventually, the eggs are released into the waters, and they’re carried in currents out into the ocean. There, the blue crab larvae, or zoea, molt up to 25 times and grow before the maturing crabs make their way back to the estuaries and salt marshes to start their own reproductive process.

Blue Crabs Will Eat Almost Anything

When it comes to their diet, blue crabs aren’t particularly picky. They eat clams, mussels, snails, dead fish, plants, and more. If they can’t find other food sources, blue crabs will even eat smaller, less mature blue crabs.

Blue crabs actually help manage the populations of the animals and fish they eat, so during periods of overfishing—as has happened in recent decades, especially in the Chesapeake Bay—the loss of blue crabs has negative effects on the ecosystem where the crabs once hunted and ate.

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