14 October 2007

Mole crab

mole crab

These things, about 2-3 cm long, were very common on the beach at the Assateague Island National Seashore, the Maryland side of the Assateague Island, late Friday afternoon. I figured they were some sort of crab, but didn't exactly know what they were until tonite when I found the following drawing in Lippson & Lippson, Life in the Chesapeake Bay (1984).

molecrabLippson

According to Lippson & Lippson, the mole crabs (Emerita talpoida) live buried in the sand within the zone of the breaking waves. Every single one I saw was dead. Had I known that there were probably many live ones buried right under our feet, I would have searched for them. Oh well, now I have one excuse to go back there...

5 comments:

Frank Anderson said...

I used to feed a congener -- Emerita analoga -- to my octopuses in Santa Cruz. We also used them for our crustacean dissections in our invertebrate zoology classes at UC Santa Cruz. Cool critters -- they bury themselves in the surf-zone sand and filter feed with those long antennae. Seems like a turbulent way to live...

Jason said...

Cool. Biomes blog recently did a Marine Life Series on mole crabs. Includes a link to a video showing them feeding.

Brenda said...

Thanks! I've always wondered what these were! My grandfather used to call them "sand fleas", and used them as bait when he fished off the Florida coast. He had a dredge-type shovel that he used to harvest them from the sand.

I always thought they looked more like crabs than fleas. :-)

Anonymous said...

These are very common on all Atlantic beaches.

They prefer water 1 to 10 cm deep, and will adjust their position almost every wave. They use the waves to move, unburying themselves when the flow is going the way they want. If they get stranded, they run a short distance down slope with their head end to the rear, before burying themselves.

There is a small (~1cm) clam that uses waves the same way, and lives in the same zone. I think they can survive being left dry for a full high tide. Maybe that makes up for the fact that they cannot run.

AJ said...

I just want to thank you for posting these diagrams. I wondered more about these things, personally I think they are disgusting! But anyways, we got to a maryland seashore, assateague island, and they are more and more of these things every year. There are literally thousands of them and I hate the feeling of them hitting the back of your ankles when the tide goes out. They don't bite (thankfully) and that is about the only GOOD thing about them. LOL! Lots of people call them sand fleas, and their name just as well should be that, because they are just as ANOYING as fleas! ;)