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| Poster #238 Osmotic and Dehydration Challenges Shape Earthworm Behavior in their Soil Environment. |
| Jonathan G Mebrahtu 1, Folashaye E Araromi 1, Ameena A Mohassib 1, Laura Ortega-Damian 1, Diana M Quiroz-Ruiz 1, Tania C Romero1, Rebeca V Rodriguez 2, Cecil J Saunders 1,2 1Department of Biological Sciences, Kean University, Union, NJ, United States 2School of Integrative Science and Technology, Kean University, Union, NJ, United States |
Earthworms crawl along a tightrope balanced between contrasting osmotic challenges. The thin film of moisture covering earthworm epithelium allows them to respire, but it is incredibly sensitive to either dehydration or becoming waterlogged. Similarly, ions essential for homeostasis are scarce in their soil environment but are desiccating in high concentrations. Thus, we hypothesized that the European nightcrawler (Dendrobaena veneta) would demonstrate a preference for moderately moist soil and dilute salt solutions while avoiding extremes of moisture or osmolarity. We utilized two behavioral assays to test these hypotheses: a burrowing assay to measure aversion and a 2-choice T-maze paradigm. In the burrowing assay, a worm is placed on a mixture of soil and aqueous solution and, after 10 min, scored as burrowed if the head is under the soil. While we found that % soil moisture (v/w) had a significant effect on burrowing (ANOVA, p <0.001, n=6), there was a wide range of soil moistures (10-40%) where >98% of worms burrowed. We also tested four salts (NaCl, KCl, NaNO3, and NH4Cl) at increasing concentrations, with and without amiloride pretreatment (n = 3 to 12). A 3-way ANOVA revealed that salt type (p <0.001), concentration (p <0.001), and amiloride treatment (p <0.001) all significantly influenced the burrowing. For the 2-choice paradigm, we designed, 3D printed, and validated a soil-filled inverted T-maze. In our initial experiments, we compared 0-50% soil moisture to 30% soil moisture and found that earthworms significantly preferred >20% moisture (ANOVA, p<0.05, n=6). We are continuing to test the earthworm’s preference between differing osmotic conditions to better characterize how these animals detect and respond to various osmotic conditions in their soil environment. |