North Carolina Marsh Critter Series: Blue Crabs!

Blue Crab (Callinectes sapidus)

The blue crab and its relatives (collectively called Portunids) are swimming crabs characterized by a pair of “paddles” that are used for swimming, an elongated carapace (shell) with pointy ends, and some very nimble claws on the front end.

You may see them in the shallows as they swim away to avoid you. Corner a blue crab and you’ll be threatened by sharp claws that won’t hesitate to grab your fingers if you get too close!

Blue crabs are both a critical part of the marine food chain and a commercial crop for humans. You are likely to see commercial crab traps in the marsh, with floats identifying the owner of the trap. Traps are private property and messing with them can mean a hefty fine and a misdemeanor, so look, but don’t touch!

Like many other marsh animals, blue crabs start out as planktonic larvae, drifting with the currents until they grow heavy enough to sink to the bottom. That’s where they will stay the rest of their life, scavenging and hunting through the sand and seagrasses that make up the salt marsh. The expansive salt marshes between Masonboro Island and the mainland are a great habitat for juvenile crabs, who eventually migrate to deeper water as adults.

Blue crabs are by no means at the top of their food chain. They are eaten by fish, other crabs, and birds, especially when they are still small. Like so many other creatures in the marshes, their activity is an important part of cycling nutrients and calories through the system.