Collaborative Research: Sensory Reception and Predator Evasion in Crustacean Zooplankton

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Researchers evaluate the role of neuromotor processes in predator-evasion by calanoid copepods. These copepods are among the more numerous animals on earth, outnumbering even insects. Despite their importance to oceanic ecosystems, critical understanding is missing on how these animals survive and, indeed, thrive in an ocean full of predators. Investigators are examining, for instance, the rapid, forceful escape behavior in which copepods seem to 'jump' instantaneously away from an approaching predator. They hypothesize that escape behavior exhibits distinctive variations among species, reflecting differences in survival strategies for animals inhabiting different environments in the ocean. Differences in physiological and behavioral characteristics of escape triggered by minute water movements are being correlated with structural features seen in the nervious system, aided by an electron microscope. Investigators are particularly interested in the presence or absence of "myelin," a protective sheathing around nerve cells. Myelin speeds nerve impulse conduction, thus shortening reaction times. Properties of the copepods' nervous systems are being related, too, to sensitivity to water movement, sensitivity to changes in light intensity (mimicking the shadow of a predator), reaction time, movement of appendages, energy production, response duration, swim speed and escape distance. In sum, researchers are providing quantitative information on the copepod's nervous system's unusual sensory and physiological capabilities.