Archive for June, 2011
Mole Crabs in the Wash Zone
Tuesday, June 14th, 2011
Wash Zone where mole crabs can be seen
I remember when I first “met” them. I was on the beach at Cape Cod with my family when I was 8 or 10. Chasing the waves, the waves chasing us, and digging in the sand, ah, the beach as a youngster. I picked up a scoopful of sand in my two cupped hands, then, “Ahhhhhhhhhhhh” accompanied by a frenzied dance flinging the sand hither and yon.
“What’s the matter?” my dad asked, as he and my older brother came to my rescue.
“There’s something in there,” I managed to eek out, “in the sand. It scritched me.”
Well, that got my brother on the case right away and he scooped up sand of his own. “There’s nothing in here. What a girly-girl you are.”
“There is too! That sand,” I said, indicating the place where waves were washing in and receding.
He scooped up sand from the wash zone, and boy did he jump too. I don’t think he emitted the girly shriek that I did, but he was startled nonetheless. Very satisfying for a little sister to see. I don’t remember if it was he or Dad that finally held onto a handful of sand with “scritchy somethings” in it, but we finally revealed the culprit.
In his hand was a little mole crab that was digging down, down, down into the sand as it does after a receding wave. Only thing was, it hit a hand instead, and boy did that tickle. Now that we knew, it was fun to catch them.
Mole crab at Cape Cod
Now, some 40 years later, walking barefoot along the wash zone on Cape Cod near Falmouth, Massachusetts, I experience them again. No screaming this time. I catch a glimpse of hundreds of them scoot ocean-ward in each receding wave before disappearing into the sand. This time the naturalist in me wants to examine these curious little creatures and learn a bit more about them. I scoop up a handful of sand and present it to my husband. “Wanna see a mole crab?”
I dig down into my handful of sand, snatch it out and rinse it off in the next wave. “Wow, that’s cool,” my husband said. I’m not sure if he remarked about my magic trick of pulling a crab out of a handful of sand or the little creature itself.
My "scritchy" friend, the mole crab
The thing is about an inch long, and is oval and domed; a light gray color, very much like the sand it lives in, making it wonderfully camouflaged. We see the feathery antennae the mole crab uses to catch plankton and small detritus the waves bring. Its appendages get tucked in neatly to make it quite hydrodynamic. Good thing, as the tide recedes, it has to go along too, so it scoots or gets rolled by an outgoing wave and quickly buries itself before the wave disappears so it is not dinner to a shorebird. It can bury itself completely in about a second and a half, hind end first.
These mole crabs I met are Emerita talpoida the mole crab found on the Eastern US coast. The west coast has Emerita analoga, the Gulf Coast Emerita benedicti and other coasts around the world have different species, but all belong to the genus Emerita.
So, on your next trip to the shoreline, dig in, and don’t scream. The small crabs are not only fun to experience but remarkable in that they live in such a small and harsh habitat as the wash zone.