Tadpole Body Zones Differ with Regard to Strike Frequencies and Kill Rates by Dragonfly Naiads
We assessed Anax junius dragonfly naiad strike frequencies and kill probabilities against Rana sylvatica (Wood Frog) tadpoles. Strikes fell into five categories according to their placement on the tadpole body: anterior head/body, posterior head/body, head/body-tail intersection, anterior tail, and posterior tail. The kill probability was calculated for each category as the number of kills divided by the number of contacts made in that category. These probabilities varied; a higher probability was found for both the anterior and posterior head/body, and values declined for successively posterior categories. Neither the kill probability nor the size of the body zone influenced the number of strikes to that zone. Surprisingly, the dragonfly naiads struck most frequently at the relatively narrow region of the head/body-tail intersection, suggesting that dragonfly naiads may aim at a specific target.Abstract
Dorsal and lateral view of a Rana sylvatica tadpole.Lines designate body zones (left to right): anterior head/body, posterior head/body, anterior tail, posterior tail. Middle line is head/body-tail intersection (BTI)
Distribution of strikes by Anax junius dragonfly naiads on Rana sylvatica tadpoles that are swimming (white) and not swimming (black).Gray line shows percent of strikes that are lethal at each location (kill-to-contact ratio · 100). Categories on the x-axis are: anterior head/body, posterior head/body, head/body-tail intersection, anterior tail, posterior tail (n = 111 interactions)
Contributor Notes
(KEJ) University of Michigan, Program in Biology, Kraus Natural Science Building, Ann Arbor, Michigan 48109-1048; and (LE) University of Michigan, Department of Ecology and Evolutionary Biology, Kraus Natural Science Building, Ann Arbor, Michigan 48109-1048. leidieti@umich.edu. Send reprint requests to LE.