  Planktonic copepods are small crustaceans that have the ability to swim by
quick powerful jumps. Such an aptness is used to escape from high shear
regions, which may be caused either by flow per- turbations, produced by a
large predator (i.e., fish larvae), or by the inherent highly turbulent
dynamics of the ocean. Through a combined experimental and numerical study, we
investigate the impact of jumping behaviour on the small-scale patchiness of
copepods in a turbulent environment. Recorded velocity tracks of copepods
displaying escape response jumps in still water are here used to define and
tune a Lagrangian Copepod (LC) model. The model is further employed to simulate
the behaviour of thousands of copepods in a fully developed hydrodynamic
turbulent flow obtained by direct numerical simulation of the Navier-Stokes
equations. First, we show that the LC velocity statistics is in qualitative
agreement with available experimental observations of copepods in tur- bulence.
Second, we quantify the clustering of LC, via the fractal dimension $D_2$. We
show that $D_2$ can be as low as ~ 2.3 and that it critically depends on the
shear-rate sensitivity of the proposed LC model, in particular it exhibits a
minimum in a narrow range of shear-rate values. We further investigate the
effect of jump intensity, jump orientation and geometrical aspect ratio of the
copepods on the small-scale spatial distribution. At last, possible ecological
implications of the observed clustering on encounter rates and mating success
are discussed
