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Kristina Timmerman


During our ecology course in the Galápagos Islands (2019), we became curious about the feeding patterns of the sally lightfoot crabs (SLC). We hypothesized that a relationship existed between crab feeding patterns and the tide levels. Our research was conducted on the shores of Puerto Baquerizo Moreno, San Cristóbal, in the Galápagos Islands. Between June 12th, 2019 and June 22nd, 2019, we observed crabs during both high and low tide. The crabs were placed into three different age groups based on their coloring: juvenile, intermediate, and adult. We collected the number of crabs observed eating at each given time from each age group. We expected there to be a greater amount of crabs eating during low tides due to the larger amount of rocks being exposed which house the algae and nutrients that the crabs eat. Our results yielded a chi squared value of 0.42 which did not support our hypothesis that crabs favor low tide for feeding. With this being said, the results did exhibit a trend that indicated crabs favor eating during low tide as opposed to high tide. We also documented that adult crabs exhibited aggressive behaviors toward other age classes. This caused many of the smaller and younger individuals to hide or move to a different area disrupting their feeding and potentially reducing total intake of daily nutrients. Our study gives more insight as to the behaviors and feeding patterns of the SLC. To better understand the feeding patterns of the SLC in the Galápagos Islands, more studies need to be conducted on the species in general about their behaviors and feeding habits.