Finding Food in an Aquatic Desert: How cruising copepods detect their next phytoplankton meal

Abstract

Copepods exist in an aquatic food desert where finding food is difficult given the constraints of their environment. They live in a three dimensional world and must filter 106 times their own body volume to cover their nutritional needs (Kiorboe, 2011). Copepods sense chemical, hydromechanical or both cues for prey and mate detection. Hydromechanoreception is the dominant sensory mechanism used to locate nearby prey (Legier-Visser,et al. 1986, Goncalves et al. 2014)). However, it is relatively unknown how copepods detect their prey from a distance. This study focused on the sensory mechanism and behavior of an abundant pelagic copepod, Temora longicornis, tracking a co-occurring phytoplankton prey, Tetraselmis suecica. The wake of a mobile prey was mimicked in the form of a trail-like cue and scented with either the smell of T. suecica, female T. longicornis, or remained scentless. Males were exposed to all three treatments, whereas females only to T. suecica and a scentless trail. Preliminary results indicate that male and female T. longicornis copepods may rely on chemical and hydromechanical cues for prey detection. Why it is important to determine the mechanism copepods use for remote detection of prey? The ocean contains numerous tiny trails scented with the smell of phytoplankton which leak from the source prey patch. It has been suggested that trail-sensing copepods will be more successful at finding mates and food than those who do not follow trails (Yen et al., 2010). Results from this study may open a new avenue of research for the success of trail-sensing organisms.