Age-related changes in movement patterns in the fishing spider, Dolomedes triton (Araneae, Pisauridae)

Based on the pattern of movement used during the search for prey, predators can generally be placed into one of two categories: active or passive searchers. This study documents an age-related switch in the movement pattern of the pisaurid spider Dolomedes triton. Individual spiders were marked and Followed during two consecutive seasons on two ponds at the Patuxent Wildlife Research Center in Laurel, Maryland. Mean distances moved per day were compared between adult females and juveniles. During both years, and on both ponds, adult females traveled significantly greater distances per day than did juveniles (1.88 +/- 0.33 m vs. 0.19 +/- 0.02 m for adult females and juveniles, respectively; years and ponds pooled). This shift suggests an age-related difference in foraging strategy. Repeated observations on individual female spiders support the notion that juvenile D. triton switch to a more active search mode upon maturation. It is hypothesized that this change in movement represents a switch in foraging strategy in response to increased energy requirements during yolk production.