ARP, A.J.: The Ecology and Physiology of the Marine Echiuran Worm, Urechis Caupo: a model animal for demonstration of physiological principles.

Urechis caupo is a large echiuran worm endemic to the California coast. Populations of these worms inhabit individual, well ventilated, U-shaped burrows in the marine mudflat. Urechis is a non-selective filter feeder which uses an intricate mucus net to trap its particulate food. Although enriched in organic material, the mudflat habitat is subject to periodic exposure to toxic sulfide and hypoxia during low tide events. Over the last 14 years our laboratory group has investigated the ecophysiology of this animal — including the ecology, behavior, morphology, physiology, metabolism, and cellular biochemistry that allow it to flourish in the challenging mudflat environment. One overriding observation has emerged: this unique echiuran worm demonstrates numerous specialized adaptations that provide an excellent demonstration of a variety of physiological principles. This presentation will attempt to synthesize all we have learned from ecological and physiological studies, starting with Fisher and MacGinitie 1928, into an overview of the natural history and biology of this unusual animal, and will highlight the usefulness of Urechis as a model in the teaching and research laboratory.