Orientation and migration are essential components of most animals' life-history patterns, permitting them to find and exploit favorable environmental conditions, locate and capture prey, and engage in reproductive and other social activities. An individual's ability to produce precisely timed movements coordinated with peak environmental and social conditions must depend heavily on its capacity to process and respond to relevant sensory information from both its internal and external environment. Dr. Sydlik will examine the role of local environmental factors in the migratory movements of horseshoe crabs. These animals are ideal for such a study because (1) major environmental factors (lunar and tidal cycles, time of day) that influence the timing of their migrations are known, (2) large numbers of animals migrate repeatedly over short distances, ensuring availability for study, (3) we have extensive knowledge of their sensory systems, and (4) Dr. Sydlik's preliminary work indicates that ultrasonic tracking can be used to collect precise data on the timing and paths taken into and away from shore during migration. Data from ultrasonic and environmental transmitters carried by the animals, and from a submerged stand-alone environmental- monitoring unit, will be collected and processed by computers housed in a van located near the shore. Using these data, Dr. Sydlik will evaluate the influences of water depth, surge direction, salinity, temperature, pressure, and flow rate over the animals' shells in stimulating and directing the migratory behavior of these long-lived marine invertebrates.
