Dr. Charles Epifanio
Size: Up to 9 inches (23 cm) wide, with the shell being half as long as it is wide.
Range: In Atlantic Ocean from New York to Gulf of Mexico.
The best description of the blue crab is the translation of its scientific name, Callinectes meaning "beautiful swimmer" and sapidus, meaning savory. Blue crabs can walk rapidly over the seafloor on their walking legs, or they can swim sideways at a good speed. This sideways swimming is unique among crabs.
The blue crab uses its claws to catch and eat a variety of food, from sea lettuce to clams. While the tips of the male's claws are greenish blue, the female's claw tips are red. Watermen say she "polishes her nails."
Female blue crabs may lay up to 9 million eggs each year!When blue crabs hatch in the Delaware Bay in July and August, wind and river flow transport them out into the ocean where they spend the first few weeks of their lives. At this point, the baby crabs look like tiny dots. Winds later position large numbers of these larval crabs near the Delaware Bay's mouth where tides help carry them back into the bay to mature.
Blue crabs support one of the most valuable fisheries along the U.S. Atlantic coast. Fishermen typically use fresh, oily bait such as bluefish in their crab pots to catch blue crabs. Steamed blue crabs and fried crab cakes are a favorite of many coastal residents.
For more information on the blue crab, check out the Blue Crab bulletin in our Sea Grant publications catalog.
For additional facts and culinary tips, check out "Blue Crab" in our Shellfish Facts. For dozens of award-winning crab cake recipes, please see our Coast Day Crab Cake Cookbook in the Sea Grant publications catalog.
Faculty Research: Dr. Charles Epifanio
"From an economic standpoint, the blue crab is the most valuable shellfish in the Mid-Atlantic region, so it's critical that we understand the factors that control its population," says marine biologist Charles Epifanio. "While fishing pressure is one concern, natural factors such as winds and currents can have serious impacts on the blue crab during its early life stages."
In interdisciplinary research funded by the University of Delaware Sea Grant College Program, Epifanio and oceanographer Richard Garvine are pooling their talents to map the natural forces that dictate the blue crab's itinerary in its first few months of life.
The scientists have modeled the dispersal of the larval crabs in the bay using real wind and river discharge data. The model shows that larval crabs are carried rapidly southward by the Delaware Coastal Current. As the coastal current decreases in strength, summertime winds can then transport larvae northward for re-entry into the bay.
In novel research last summer, the scientists deployed drifters in patches of crab larvae outside of Delaware Bay. The drifters contained satellite-tracking devices, which revealed the crab's locations over a 12-day period.
"Our study is one of very few that have tracked patches of fish or crabs in the coastal environment," Epifanio notes. He says the data indicate that as river discharge decreases in late summer, wind effects on larval transport increase. Thus, the supply of larval blue crabs may be maximum in drought years when river flow is at a minimum.