More on Mole Crabs

Thanks for all of the comments about mole crabs! My students and I enjoyed reading the comments. Several of you had some great questions about the little crabs. Here are some answers.

How big do they get?
The mole crabs that we find at the beach (Ocean City, Maryland or Assateague) are usually 1.5 inches or less. You can see Zachary holding one in the picture. That's one of the bigger ones that we found. The smaller ones are about .5 inches.

Can they live in Lake Erie?
I don't think so. It's my understanding that they are saltwater creatures. Lake Erie, as you know, is freshwater. But I'd love to research and find out more.


Can mole crabs be different colors? 
Life is tough if you are a tiny (and delicious) little crab. Why do you think that mole crabs are the color that they are? Where might you find mole crabs that have different colors?

Why do mole crabs stay in wet sand?

Good question! The mole crabs are filter feeders. They stay close to the waves because they put their antennae up to feed when a wave comes by. Because this is how they eat, they like to stay in the wet sand.

Why are they called mole crabs?
When I started researching them, I was actually surprised to find that this is their most well-known name. We always called them "sand crabs" when I was growing up.

But the name makes sense. If you happen to be at the beach while they are digging down into the sand, they do look like moles digging into the ground. Moles dig, and these crabs dig, so the name fits!

Ghost crabs

This tiny ghost crab blends in perfectly with the sand.

If you visit the beach in the evening, you might see some of these small crabs scurrying by. Ghost crabs can blend in almost perfectly with the sand, which makes them hard to see. They are also very fast. No wonder they are called ghosts!

Ghost crabs don't live in the surf, like mole crabs. Instead, they dig holes further up the beach. Sometimes you can even see them tossing grains of sand out of their holes.

If you want to see a ghost crab, visit a quiet Atlantic beach at twilight or early morning. Find one of the small ghost crab burrows. You can try waiting beside a burrow for the crab to come out. Ghost crabs have to leave their burrows at night to go to the water so that they can wet their gills. They also scavenge for food along the beach, eating just about anything they can find.

Another way to see a ghost crab is to walk along the beach with a flashlight. The light can often catch the shadow of a crab hurrying down to the water. If you are lucky, the crab might pause, surprised by the light. Carefully kneel down to see it more closely. You may notice how its eye stalks stick out. Look carefully at the crab's amazing camouflage.

Ghost crabs are fun little creatures to observe. Try to find some!

Mole crabs: Tiny creatures of the surf

Look carefully at this mole crab. Its head on the right side of the photo. Can you see its antennae peeking out?

Imagine living in a place where the salty ocean water crashes against you. Where every wave pounds against the sand, a place of noise and crashing water. To the tiny mole crab, this is home sweet home.

If you have ever visited a beach, you have probably seen one of these creatures. They are one of the few creatures to live in the area of the beach called the surf zone, where the water meets the sand. Like other crabs, mole crabs have ten legs. If you have ever held one, you probably know that they love to dig!

This digging is what helps them to survive in the surf zone. Mole crabs always dig backwards into the sand. As waves crash over them, they stick out their antennae. Bits of food are always churning about in the ocean water. These food bits stick to their antennae. Then the mole crabs can eat the food!

Digging also helps mole crabs to escape from predators. Sea gulls find them pretty tasty. Larger crabs, like ghost crabs, will also eat them. And people often collect mole crabs to use as bait for fishing.

But mole crabs are more than just prey. They are fascinating little creatures, tiny crabs that live in a harsh place. Mole crabs can be found in many different areas, and have many different names. In some places, they are called sand crabs. They are also called beach hoppers.

The next time you find one, observe it carefully. Can you find its antennae? How many legs does it have? Can you see it digging backwards? These little creatures have a lot to share!