Oceanic lobate ctenophores possess feeding mechanics similar to the impactful coastal species Mnemiopsis leidyi

Abstract

Lobate ctenophores are often numerically dominant members of oceanic epipelagic and midwater ecosystems. Despite this, little is known about their trophic ecology. Multiple, co-occurring species are often found in these ecosystems and appear to feed similarly via feeding currents that entrain prey. We quantified the hydrodynamics, morphology, and behavior of four co-occurring, cosmopolitan lobate species (Eurhamphaea vexilligera, Ocyropsis crystallina, Bolinopsis vitrea, and Leucothea multicornis) to evaluate whether their feeding mechanics lead to differential feeding rates and prey selection. We compared the feeding characteristics of these four oceanic species to the coastal lobate ctenophore, Mnemiopsis leidyi, which is known as a voracious zooplanktivore. We found that despite their morphological diversity, the five lobate species used the same mechanism to generate their feeding current — the hydrodynamics of their feeding currents were similarly laminar and with very low fluid deformation rates. Despite having similar feeding current traits, the species had different in situ swimming behaviors and feeding postures. We show that these different behaviors and postures lead to different prey encounter rates and that several of the oceanic species have the potential to feed at rates similar to or greater than M. leidyi. As such, the individual and combined trophic impact of oceanic lobate ctenophores is likely to be much greater than previously predicted.