Blue crab (Callinectes sapidus) lives through the Atlantic Coast and in the Gulf of Mexico. The blue crab shell, also called a carapace, is blue to olive green, the shell can reach 9 inches across. The claws are bright blue, with mature females having red tips on the claws as well. They have four pairs of legs, the first three are walking legs, while the last rear pair are swimming legs that look like paddles.
Blue crabs can live up to 3-4 years, reaching maturity at about 12 to 18 months. Water temperature does affect growth rates, they grow more quickly in warm waters. In the Gulf of Mexico, they can mature in about a year, but in the Chesapeake Bay, it can take up to 18 months. As the crab grows, it will “molt”, which is shedding its hard shell. When molting occurs, they will lose their hard parts, which can make it difficult to determine age. Males will molt multiple times during their lives, while females will only molt once, which is before mating. Blue crabs are bottom-dwellers, beds of submerged aquatic grasses are used for food, nursery habitat for young, and shelter during mating and molting.
These shellfish are important predators of benthic communities and are prey for many fish species. They will eat almost anything, including clams, oysters, mussels, smaller crustaceans, freshly dead fish, plant, and animal detritus, and other blue crabs that are smaller and soft-shelled. Crabs become prey to large fish, some fish-eating birds, such as great blue herons, and sea turtles.
When mating occurs, a male will cradle a female in a pose known as a “doubler” for a few days before her last and only molt. The male will stay with her after mating until her shell hardens, to ensure no other male will mate with her. When the eggs hatch the larvae will go through multiple molts in high-salinity coastal waters.
Cool Fact! Callinectes sapidus is translated from Latin which means, ‘beautiful savory swimmer’.
Photo Credit: Bobby Putnam
Author: Destiny Alvarez – Fisheries and Wildlife Sciences, University of Oregon
