Crustacean Revelation

Article by Langley Murray Art by Avy Diamond

What knowledge does the crustacean soul hold? 

 A kid smushes their face against the thick, acrylic glass separating them and their new friend. The fluorescent lighting in PetSmart makes the SpongeBob painted on its shell excitingly enticing. Deep-red, stubby legs curiously begin to emerge from the shell, followed by two unthreatening claws, and finally, two spindly fixtures with round, luminous black eyes poised on the tips. They stare curiously back at the child — these ten seconds of eye contact are all it takes to convince the kid that the hermit crab needs to come home.  

The hermit crab is welcomed into its own little tank on the kid’s nightstand in semi-arid Pueblo, Colorado. It has a bed of sand, a bowl with fresh water, some pieces of driftwood, a pineapple-shaped cave, and a platter with the finest hermit crab diet pellets — all a hermit crab could ever want or need.  

For the first week, it happily scuttled around its tank, rearranging things as it saw fit. As the months went by, the child periodically noticed the crab lapse into some sort of stasis; it would bury itself in one of its four corners, shrink deep into its shell, and remain immobile for days and days. Panicked, the child would take it out to play, dunk the crab in water, offer it a new shell; but nothing could shake the crab of its cold-blooded blues. Just as the child began to lose hope, and the parents begrudgingly prepared their speech on grief and the cycles of life, the crab spurred into a sudden state of hyperactivity. It ceaselessly scoured its little world, rooting through the sand and turning over all its rocks, bringing waves of relief to the family. These episodes repeat in a cyclic, sporadic manner seemingly invoked and repressed by nothing except the crab's own whims. This confused the shit out of the parents and child alike, leaving them wondering: is this the crab equivalent of bipolar disorder? What is going on in that crustacean soul?  

Little does the family know, their new pet is responding to some thalassic force. Hermit crabs cannot be bred in captivity, consequently all “pet” hermit crabs are wild caught from some far-off warm beach, maybe in the Caribbean. Hermit crabs (along with many other intertidal organisms) exhibit these cyclic behaviors in response to the tides. Their displaced, captive counterparts still exhibit this — seemingly responding to tides — despite being moved thousands of miles away from the ocean. The biological underpinning of this behavior is a complex, genetically encoded internal rhythm. Instead of having a circadian rhythm, researchers have dubbed the internal rhythm phenomenon of hermit crabs a “circatidal” rhythm, which allows these creatures to constantly be in tune with their environment and respond to the ever-changing cyclic nature of the ocean. These internal rhythms have been shaped by thousands of years of evolution in tandem with the ocean; those behaviors have been ingrained in their souls, so no matter where they end up, they will always feel the pull of the ocean. Even though the crab now resides on a nightstand in dry, landlocked Pueblo, Colorado 800 miles away from the ocean, it feels the tides and acts accordingly. They are living proof that you can exist in two states at once.  

I feel the pull when I go to pick out tomatoes in the grocery store. They overused GMOs, none of them will taste as sweet as the ones grown in my mom and I’s garden. I feel the pull when I’ve grown too big for the shell I carry, and it’s time to try on a new one that fits me as I am now. When I’m on the roads here, I feel enraged at the Coloradans who don’t know how to use the left lane. I use my pinchers to scrounge up a morsel of tasty food from my new substrate, a skill I perfected elsewhere. Sometimes I wake up in the morning and look out my window, expecting verdant forest and disorientedly searching for the call of a Northern Cardinal. In their place I find mountains and Steller's Jays. This is the poetry of the hermit crab.  

In the end, we never fully understand the forces that shape us — whether they are the tides that guide a hermit crab or the invisible currents pulling at our own hearts. The crab's restlessness reminds me that we are always in motion, sometimes caught in stillness, sometimes caught in wild activity, but always moving toward something, even if we can’t see it. Maybe the ocean doesn't call us all in the same way, but we all carry that rhythm inside us — the ebb and flow of who we are and who we’re becoming. 

 

Sources: 

  • Sakich, N. B., Bartel, P. C., Richards, M. H., & Tattersall, G. J. (2023). Hot crabs with bold choices: Temperature has little impact on behavioral repeatability in Caribbean hermit crabs. Behavioral Processes, 210, 104916. 

  • Naylor E. (1985). Tidally rhythmic behavior of marine animals. Symposia of the Society for Experimental Biology, 39, 63–93. 

  • Zhang, L., Hastings, M. H., Green, E. W., Tauber, E., Sladek, M., Webster, S. G., Kyriacou, C. P., & Wilcockson, D. C. (2013). Dissociation of circadian and circatidal timekeeping in the marine crustacean Eurydice pulchra. Current biology : CB, 23(19), 1863–1873. https://doi.org/10.1016/j.cub.2013.08.038