The Crab and the Fiddle

Scott Akerman on Flickr’s photo of a bustling colony of fiddler crabs

When I was in the fourth grade, my amazing science teacher brought in not one, not two, but dozens of little frogs, fiddler crabs and meal worms to be our temporary class pets. Okay, they were actually there for us to study and do little experiments with, but we would be taking them home at the end of the unit and basically thought of them as pets from the get-go. Most of my friends wanted frogs, but I claimed a little fiddler crab and named her “Speedy.”

I used to think that everyone gave their pets and toys dumb names when they were little, but the number of times my parents have made fun of me for Cowie, Sealy, Giraffy, etc. makes me wonder if that was just a me thing. Hmm… maybe I should give the arthropod-naming people some slack this week, naming animals is harder than I often acknowledge on this blog.

Speaking of naming things, fiddler crabs get their name from the way male crabs seem to hold their larger pincer like a fiddle. I myself would’ve just called them Hey Crabs, because the ones I see in the marsh are always waving their claws up and down like they’re saying “hey” to each other. Interestingly enough, another name for fiddler crabs is “calling crabs,” which I am definitely going to use now.

In actuality, calling crabs are neither making music nor calling to each other when they wave. Instead, they wave to get rivals to back off their turf or beckon potential mates. Male crabs will also use their large claw to fight with one another over burrows or females. While having a long, lightweight claw is ideal for attracting mates, males with heavy claws have the advantage in claw-to-claw combat.

Despite the fact that most calling crabs are just over an inch in length, their burrows can be as deep as two feet! Calling crabs stay inside their burrows during high tide, blocking up the entrance with mud to keep out the water. They can also quickly slip into their burrows during low tide if they spot a predator approaching – or if you get just a little too close for comfort trying to take their picture, as I have learned from experience.

Aside from serving as an escape route, calling crab burrows are thought to aerate the mud in marsh habitats. These tiny crustaceans also contribute to their ecosystems by eating bacteria and algae out of the mud, and serving as food for a variety of larger animals like fish and shorebirds. You can find fiddler crabs in a variety of tidal areas along the coast, including mudflats and saltmarshes.

Calling crabs typically live in large colonies, so if you spot one, you’re sure to find plenty more nearby. Because the house we stay in is on the sound, my family and I run into calling crab colonies all the time during our annual beach trip: we might kayak around a corner and see a whole city of fiddler crabs waving at us from under someone’s dock. Of course, they all disappear into their burrows the second you get close enough for a good picture, but they’re still fun to admire from a distance.

Did you know calling crabs use their little claws like sporks to scoop food out of the mud and bring it to their mouths? Because males have one big, fancy claw and only one little claw, it takes them twice as long to eat as females. As Larry the Cucumber would say, “fashion has its price” (if y’all don’t know what VeggieTales is, click that hyperlink for a “sweet and sour half an hour” of high-quality children’s programming).

While Speedy was a fun pet, I don’t know that I would keep a fiddler crab again. She had sand and saltwater, and the terrarium I got her in was about the size of the one she had in the classroom, but looking back I think she was probably lonely without the rest of her colony. Calling crabs are social crustaceans that need others to, you know, call to.

In other words, if I ever decided to get fiddler crabs again, it will be fiddler crabs, plural. These guys would really fare best left in their natural habitat, but if the opportunity ever arises for me to adopt a colony of fifty calling crabs or whatever, you would find me converting the living room into a mini marsh in a heartbeat.

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