Prey Detection and Feeding Success of the Comb Jellyfish Mnemiopsis leidyi on Copepods in Still and Turbulent Waters

Abstract

The comb jelly or ctenophore, Mnemiopsis leidyi, is a voracious predator in both its native and non-native habitats. Though M. leidyi inhabits coastal waters that are frequently turbulent, previous feeding studies have been conducted in still water tanks. This study aimed to research feeding behaviors in turbulent waters, which is more representative of the natural environment. Interactions between the free-swimming ctenophores and copepod prey, such as Acartia tonsa, were observed and recorded in a laboratory turbulence tank (n = 73). Turbulence was created using submersible speakers, and the interactions were recorded using a video camera. Capture efficiency denoted interactions containing direct contact between copepods and M. leidyi that led to eventual capture, frequently after multiple contacts. Overall copepod capture efficiency was similar in still (48%) and turbulent (43%) water, as were the overall prey retention rates for each (still = 58%; turbulent = 57%). However, M. leidyi exhibited anticipatory responses, defined as altering the position of feeding structures, nearly twice as often in still (41%) waters than in turbulent (20%) waters. The hydromechanical “noise” produced by background turbulence may inhibit the capacity of the ctenophore to detect and respond to fluid motions produced by its prey.