The Blustery Month of May

I remember a song from “Camelot” that rhapsodized on the “lusty” month of May, but here on the Cape, at least for the last week, it has been the “blustery” month of May. A storm is spinning off the coast and seems content to sit there, so we have been treated to temperatures in the 40’s and 50’s accompanied with sheets of mist, rain and more mist. Walking the bog it looked more like a winter snowstorm than a spring shower and I, wrapped in winter scarves and gloves, could have been contemplating Christmas shopping instead of wondering how to get a frog in such weather.

More challenging than frogs however, was the need to find fiddler crabs for a salt marsh program. My co-worker and friend Andrea is a magnet for all things wild, so following her lead, we went out to the marsh at low tide. The wind was blowing like a gale and I thought “fat chance” of finding any. You wouldn’t catch me at the entrance of my burrow in such weather, not when I could go deeper in the peat and get out of the storm. Incredibly though, searching along the ditch edge on hands and knees, we actually came up with the dozen “volunteers” we needed. Think if it as crab community service. They all get returned to their home ditch as soon as the class is over. But they are part of a lesson on the energy cycle of the marsh, and they are so, so fetching that you hate not be able to show them to the students.

There are some 97 different species of Fiddler crabs but the one we find in our marsh is an East Coast fiddler, Uca Pugnax, a small rectangular crab no more than 1.5-2” long but grand to behold all the same.
The male is said to have “extreme chiliped asymmetry” which, in simpler terms, means he has one claw that is a lot larger than the other and it is this large claw that gives it its name.

Now, the “extreme chiliped” is all for the purpose of attracting the ladies, and for defending its territory. I knew the male waved the claw around to impress the women, but what I didn’t know was that by doing so it makes a sound that is music to the lady fiddler’s ears. If she is impressed with this display she will follow him down into his tunnel, and well, you can guess the rest.
I also read that he can stamp the sediment with his walking legs, all 8 of them and also attract the ladies attention that way. Either way, it is all for show, for the fiddler can neither eat with that claw, nor dig out his extensive tunnel with it. And for even more irony, the larger the claw, well the more ladies maybe, but the harder it is to get through his own tunnel or to forage for food. You can see where Nature puts her priorities!

Plus, I love this, I also read that the female will sometimes attach her tunnel to his, but because of the size of that large claw it is a one-way street. She can enter his tunnel if she wishes but he could not pursue her into hers. The liberated crustacean world!

As far as male fighting, they do wave claws at each other and do a bit of arm wrestling but not a “to the death” sort of duel. A male can lose his claw that way, but he can also chose to snap it off, if say a gull or some other predator is about to lift off with him. Better to lose your one “lucky claw” and live another day, than go down someone’s gullet altogether. Plus, with the next molt, the opposite claw will become the larger one. So when I find a fiddler if it has a left claw rather than right, I assume it has either been vanquished in battle at some point or has had a near death experience with some predator.

The females have two small claws- all the better to feed yourself quickly with.
The Fiddlers diet is detritus, making them detritivores, a fun word to say on any occasion. Detritus being small decaying organisms found in the marsh mud. They eat the mud but are able to filter the good from the bad, in a way, like earthworms do. And like earthworms, whose digging aerates the soil, the tunnels of fiddlers that can be a foot or so deep, help aerate the peat. The tunnels provide them protection from predators and when the tide is high they plug the entrance with mud and wait out the return of low tide, which is their preferred feeding time.

Not to be missed either are their stalked eyes.
They can be held straight up, or lay down flat along their shell for those tight squeezes in the tunnel. Very cute to see them “boing” up or flatten down. All together, this is one amusing crab. Worthy of the wild weather we had to face to get them. Hmm, but not having done the class myself, I am not sure if any of this magic was lost on the kids in the classroom. But when they come out for their field lesson, we will have a chance to convince them once again how grand these crabs are and see how proficient they can be at catching them. But that lesson is a good three weeks away, lets hope by then the winds will have died down and the temperatures risen to a more seasonable degree. Being New England though, that isn’t a given.