UCB Moorea Class: Biology and Geomorphology of Tropical Islands

This study investigates the biomechanics, behavior, and distribution of urchin species in Mo’orea, French Polynesia to understand how they withstand hydrodynamic forces. Field surveys examined the flow distribution of four species:E. mathaei, Tripneustes gratilla, Diadema savignyiandEchinotrix calamaris. Flow tests were conducted on twoEchinometra mathaeisubspecies to measure spine angle under no flow and heavy flow conditions. Short spine urchin species were found in significantly higher flows than were long spine urchin species. Experimental findings revealed thatE. mathaeitype B temporarily adopts a more streamlined shape in response to increasing flow velocity, whileE. mathaeitype A does not. Understanding the streamlining behavior and other strategies for surviving hydrodynamic conditions is necessary in order to examine these organisms’ role in their environment.