Centipede

Zack's centipede Zack Loehle, my classmate in David Haskell‘s nature writing class, found the topic for his Shakerag Hollow essay underneath the litter. We learned a lot about this little critter:

Theirs is the difference between the snake and salamander, the weasel and the rabbit. The squirming of the one puts us off while we find the chubby solidity of the other reassuring; we reject the difference of the one and embrace the familiarity of the other. Or maybe we just don’t like to get bitten.

Beneath the stick and leaves nestled between two rocks perched along the forest slope sit two dissimilar relatives: a centipede and two small millipedes. Brought by my curious hand, sunlight floods the formerly dark, moist space, forcing the arthropods to run towards the safety of the leaf litter. Where the millipedes barrel through the dirt in what appears to be a straight line, the centipede squirms and twists its body this way and that, legs dancing across the stone surface in an erratic rush towards safety. It changes direction several times in a row, moving from side to side, back end of the body not following the front until the last possible minute.

When I pick it up and hold it in my palm it freezes, still down to the antennae. Forest noises filled the waiting air as the arthropod continues to hold its stillness. Then, without warning, it begins to run again, fifteen leg-pairs moving in unison across the unfamiliar pink landscape of my hand, then my arm. Its movement lacks any hesitation. Spiky legs jumble across skin towards the arm, the sleeve, then switch; now they run along the back of the hand, out to the edge of the fingertip, where, instead of slowing, the centipede speeds up, running off the edge and tumbling back onto the leaf litter. Even when running, the millipedes stopped, tested, sensed surroundings. Not the centipede.

Part of what makes the centipede’s movements so unnerving is the erratic writhing of its body. At slow speeds, centipedes can walk from one place to another in a straight line. As they pick up their speed, however, their bodies begin to undulate, snapping back and forth to a greater and greater degree as speed increases. This one moves like sound waves—with greater energy of movement, wave height increases and wave length decreases, squirming over the surface of my skin.

Their legs move at different speeds as well; when a centipede changes pace, some of the legs, located towards the back of the body, maintain the previous pace for a moment. This disjunction creates a ripple across the centipede’s body. Like dominos, the legs pick up pace one by one, following the cues of the leg-pair in front and giving the centipede its irregular motion. It moves onward, forward, over the edge of my finger.

When I look again, it has disappeared into the fallen leaves.

References

Borror, D. J. and White, R. E. (1970). Peterson Field Guides: Insects. New York: Houghton Mifflin. 50-51.

Cranshaw, W. (2004). Garden Insects of North America. Princeton: Princeton University Press. 502-503, 562-563.

Hahn, J. (2016). Stone Centipedes. University of Minnesota Extension: Insects. Retrieved from http://www.extension.umn.edu/garden/insects/find/stone-centipedes/.

Karpovich, A. L. (2008). Kinematics of nonstationary locomotion in the centipede Scolopendra cingulata: A single instant change of speed. Biophysics, 53(2), 182-187.

Klopper, A. (2013). Biomechanics: Have legs will travel. Nature Physics, 9(3), 134-134.

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One comment

  1. Pingback: Zack Loehle wins Environmental Leadership Award | Sewanee Herbarium

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