Sand fiddlers were an integral part of my childhood. My cousin and I would spend hours on the beach in the summer digging primarily for coquinas (those colorful little clams that wash up on the beach all the time), but finding a sand fiddler was always incredibly exciting. It wasn’t because they were particularly rare or anything, but because they were harder to find and catch than the clams and they were a lot more fun to watch swimming around in our bucket.
Even as an adult, I’ve always got coquinas, shark teeth and sand fiddlers on the mind whenever I’m walking down the beach. One day during this year’s family vacation, I was checking out some tidepools and ended up discovering a treasure trove of sand fiddlers that kept me occupied for a solid fifteen minutes – although it was less because I wanted to play with them and more because I had accidentally put them in mortal danger, more or less.
See, I’d come across a group of about ten or so tidepools ten yards from the tideline. Most of the pools were several inches deep, but there was one pool further up shore that was more shallow and only about a foot across but writhing with sand fiddlers. Smart me thought, “oh, I should dig a trench connecting this pool to one of the larger pools, and then it’ll all be one big pool and it won’t dry up on the sand fiddlers.” However, instead of the larger pool downhill from the little pool filling the little pool with more water, all the water from the little pool started draining into the big pool. Go figure.
I quickly realized my error and stopped up the trench with sand again, but the damage was done. The little sand fiddlers started racing around frantically as their water slowly drained deeper into the sand.
I spent the next ten minutes scooping up handfuls of sand fiddlers (it was ridiculous how many there were) and rushing them to the deeper pools. I probably should have just gotten a shovel, scooped up all the sand and dumped them back in the ocean, but it’s pretty evident now that my critical thinking skills weren’t exactly at their sharpest that day.
Y’all know I like to pick on arthropod names a lot, but the funny thing is that I usually don’t hear a lot of these names until I sit down to write these posts. I didn’t know mulch lobsters are sometimes called woodlice. I didn’t know granddaddy longlegs are really harvestmen. And I certainly didn’t know that y’all call sand fiddlers “mole crabs.”
Mole crabs. Why are these specific crustaceans the ones called “mole crabs”? Almost every other crab I know of digs in the sand too. I get that these guys probably dig faster than other crabs, but who said literal moles themselves were particularly fast at digging? I mean, they’re good at digging, but I’m inclined to believe that these guys were named for the speed at which they dig and not for the skill itself. Ghost crabs are very tidy hole-diggers; “mole crabs” just divebomb into the ground like foxes faceplanting in the snow.
Another slight difference between moles and mole crabs: moles dig headfirst, while mole crabs burrow backwards. Didn’t see that coming, did you? I always wondered why I’d never seen a face on a sand fiddler, and now I realize it’s because I was looking at the wrong end. This also explains why sand fiddlers typically don’t burrow very far underground but just sort of bury the majority of their body and leave their little heads sticking out of the sand: instead of searching for sustenance underground, the sand fiddler actually filter feeds with its antennae.
Being a literally backwards animal may sound a little strange, but the sand fiddler design is no joke: these little dudes are tough. The curve of their helmet-like exoskeletons and the positioning of their limbs under this helmet protects the tiny crabs from the relentless waves of their swash zone habitat. Some sand fiddlers have stalk eyes like other crabs, while others’ eyes remain under the hood of their exoskeleton for further protection. And remember the telson from the post on horseshoe crabs? It’s plenty important for those guys, but the tail-like structure sees a little more action as a sand fiddler appendage. The telson is what the sand fiddlers dig with, and it also keeps them tethered in the sand so they don’t get swept away by the tide.
I always wondered why these little guys bothered to stay in such a dangerous, chaotic habitat as the swash zone where the waves are constantly washing back and forth over them, but as it turns out there’s a method to their madness. Our crafty sand fiddlers are always following the current, which is why they don’t tend to stay in the same place all the time and it’s not uncommon to see them racing up shore or back towards the water. By moving with the current, which carries their planktonic prey, they’re always sure to be in the right spot to receive the most food from the crashing waves.
Unfortunately for the crabs, this habit of staying in shallow water means sand fiddlers can become easy prey themselves for a variety of shorebirds, small fish, and even larger crabs. The number of predators and said predators’ preference for sand fiddler meat make these backwards lobsters a critical staple in the coastal food web and excellent bait for beachside fishermen. However, because of their lack of weaponry to combat such predators, sand fiddlers tend to feed at night to minimize their odds of being eaten. That said, sand fiddlers are fun to handle because they won’t bite or pinch you, but try not to keep them out of the water very long so they’ll be able to breathe.
Fun fact: sand fiddlers are also known as sea lice, and since we changed woodlouse to mulch lobster I feel it’s only fair we do the same with the sea louse: I present to you the sand lobster. You’re welcome yet again for righting this atrocious wrong.
…I need to do a post on lice. We shall call them head lobsters! Or hair lobsters. I don’t know, we’ll cross that bridge when we come to it.
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