The most common crab along the New England shore is the green crab. It lives in crevices in the rocky shoreline, hiding in kelp, or under submerged rocks. The spider crab features a brownish shell that grows up to four inches across, while its legs can span a full foot. Its round shell is covered with short hairs and spines, called tubercles. They camouflage themselves by snagging algae and assorted debris to these hairs.
Spider crabs are harmless, lethargic creatures that eat sea worms, dead fish, detritis and algae.
Fiddler crabs are more commonly found along marshy tidal flats. Female fiddlers do not have the distinctive large claw. Fiddler clarbs often travel together. The sight of many fiddler is crabs also a sign of a healthy marsh. They scuttle quickly about on the bottom of pools and tidal flats scavenging for food.