(
2012-01)
Gemmell, Brad J.; Jiang, Houshuo; Strickler, J. Rudi; Buskey, Edward J.
The marine environment associated with the air-water interface (neuston) provides an
important food source to pelagic organisms where subsurface prey is limited. However,
studies on predator-prey interactions within this environment are lacking. Copepods are
known to produce strong escape jumps in response to predators but must contend with a
low Reynolds number environment where viscous forces limit escape distance. All previous
work on copepods interaction with predators has focused on a liquid environment. Here,
we describe a novel anti-predator behavior in two neustonic copepod species where
individuals frequently exit the water surface and travel many times their own body length
through air to avoid predators. Using both field recordings with natural predators and
high speed laboratory recordings we obtain detailed kinematics of this behavior, and
estimate energetic cost associated with this behavior. We demonstrate that despite losing
up to 88% of their initial kinetic energy, copepods which break the water surface travel
significantly further than escapes underwater and successfully exit the perceptive field of
the predator. This behavior provides an effective defense mechanism against subsurface
feeding visual predators and the results provide insight into trophic interactions within the
neustonic environment.
