Instructions
Examine the color of the crab. Dungeness crabs are usually reddish-brown in color, with the color darker on the front of the shell fading lighter to the back. The bottom of the crab is often orange or occasionally violet-blue. One telltale sign of a juvenile Dungeness crab is that they are green--that is a sign that they've molted their old shell. Adults molt once a year, where a juvenile might molt 10 or more times a year.
Consider the area in which you found the crab when making an identification. Dungeness crabs live on the West Coast of North America, from Alaska all the way to Mexico. The crabs enjoy aquatic environments rich in mud, eel grass and sand. If you find a small crab among other adult crabs, it's probably not a juvenile. Dungeness crabs are cannibalistic, so juveniles stay with other juveniles or live alone. Juveniles will often be found hiding under shells or within grass rather than right on the ocean floor.
Look at the depth of the water you found the crab in. Juveniles prefer shallower water, so they stay closer to the coast. As they get older, they move farther out to sea. Adult Dungeness crabs prefer water at a depth of at least 180 meters.
Examine the size of the shell. This top shell, known as a carapace, is about 7 inches wide in adults. Juvenile Dungeness crabs have much less broad shells.
How to Identify a Juvenile Dungeness Crab
Dungeness crabs are a crustacean found on the West Coast of North America. They are known in culinary circles for their tender, sweet meat. For the first two years of its life, a Dungeness crab is known as a juvenile. When catching Dungeness crabs, it's important to know the difference between an adult and a juvenile because it's illegal to fish for young crabs for food, and the adult crab meat tastes better anyway. All it takes to identify a juvenile Dungeness crab is examining its size, shape and color.