Predator or prey?

Prey behaviour is shaped by the presence of predators, modifying spatial and temporal patterns (Caro 2005, Heithaus et al. 2009). The interactions between both prey and predator are shaped by their sensory capabilities. The aggregation at resource patches usually corresponds to a high risk of predation, preys, therefore, must evaluate the pros and cons of that action (Willems & Hill, 2009).

It is not easy to understand predator avoidance techniques in marine species, but it has been documented that in low light conditions white sharks prefer to hunt close to the bottom of the water column to increase their chances to prey on Cape fur seals (Arctocephalys pusillus pusillus) located on the surface (Martin et al., 2005). When sharks are detected, seals assume a head-down posture, interrupting their travel behaviour and involving in surface scanning (Martin et al., 2005).