ABSTRACT

In this project the Investigators will examine the ontogeny of predator-evasion behavior in marine calanoid copepods. Neuroethological mechanisms underlying predator-prey interactions are fundamental to the success of planktonic species at all developmental stages. The approach will be interdisciplinary, integrating behavioral, morphological and neurophysiological studies. The specific objectives are: a) to document the development of the escape response in different life stages, from nauplius to adult, and correlate changing escape performance with the development of the sensory, motor and central nervous systems; b) to characterize the effect of variable environmental conditions on the escape of the different life stages; and c) to characterize the development of escape behavior to natural predators.
Predation is often the greatest source of mortality for planktonic organisms. Different marine taxa have met this challenge in different ways. In calanoid copepods, it has led to an escape performance matched by few other organisms. Underlying this performance is an array of unusual neuromotor characteristics evolved in response to the predation pressure, including high mechanoreceptive sensitivity, high neuronal firing-frequency capabilities and the occurrence of myelinated nervous systems in about half of all calanoids. Behaviorally it includes fast reactions to mechanical stimuli, high output of muscle energy and high cycle rates of muscle action. Conventional crustacean physiological properties cannot account for copepod escape capabilities. How these animals achieve their remarkable behavioral and physiological performance and how the performance develops from nauplius to adult, are key questions in understanding their success. Because calanoids invest so heavily in escape, the answer to these questions relates strongly to the general issue in all organisms of the role played by the neuromotor system in ecological and evolutionary adaptations. An integrated approach can shed light on this. Focus on the developmental stages will achieve several goals. As for many animal groups, overall predation risk for younger individuals (nauplii and copepodites in copepods) is higher than for adults. Studies of this susceptibility, especially as a neuroethological issue, are relatively few. The proposed work will map out the copepod's developmental strategy for increasing behavioral competence as it matures. Secondly, through studies comparing morphological and physiological features of developmental stages with those in adults, it will help us determine how and when different aspects of the neuromotor systems appear during development and how these correlate with escape performance. Finally, it will give the scientific community a much better understanding of predator-prey interactions in the younger stages.
Broader impacts include training of graduate and undergraduate students, as well as providing learning opportunities for the general public and K-12. The project will support the training of two graduate students in marine science, who will be cross-trained in areas of neurophysiology, morphology and behavioral testing. At the level of K-12 and the community we will develop a short video on biological interactions in plankton communities for public presentation and continue to develop and maintain a website on zooplankton sensory ecology

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