Ask ALOysius

When is a Crab Not a "True" Crab?

Alliance for a Living Ocean

2007 Long Beach Boulevard
North Beach Haven, New Jersey 08008
(609) 492-0222

Question:

In the summer, my friend and I love to dig for sand crabs along the water. Are they real crabs? They don't pinch us.

ALOysius:

These little animals are called Atlantic Mole Crabs. They are not "true" crabs, but they are closely related. They are completely harmless. They can not bite, pinch or sting so they are lots of fun on the beach. Even though their real name is Mole Crab, most people call then Sand Crabs.

The best way to find these little crabs is to dig a hole in the sand at the very edge of the waves. Swish the water and sand together in the hole, and you'll see the crabs darting through the water before they bury in the sand again. If you collect them in a bucket, PLEASE remember to put the crabs back in the water. Don't let them bake in the sun in your bucket all day. Aloysius wants you to treat even the smallest creatures with respect.

Question: How big do Sand Crabs grow?

ALOysius:
The Mole Crab has a light yellowish shell, and the biggest ones are about 1 1/2 inches long. These are the female crabs. The males only grow to about 1/2 inch. Mole Crabs have short, broad, flat legs which they use to dig in the sand. They do not move sideways like the "true" crabs.

Question: What do Sand Crabs eat?

ALOysius:
These crabs collect organic materials and very small creatures for their food as the wave water rushes over them. They have two feather-like antennae sticking up from their bodies which are used to catch the food. When washed free of the sand, they quickly dig back into the sand to hide, or they will become lunch or dinner for a hungry shore bird.

Question: I find lots of Sand Crabs during the summer Why can't I find them the rest of the year?

ALOysius:
In the warmer months, the Mole Crabs live near where the waves break on the sandy beaches. They move up and down the beach with the tide. They are constantly burrowing in the sand after being washed free by the waves. In the colder weather, they move away from the shore into deeper water where they can swim free. That's why you can no longer find them on the beach.

Until next time.

ALOysius