A Study of the Feeding and Predatory Behavior of the Ctenophore Beroe abyssicola

Abstract

Beroid ctenophores such as Beroe abyssicola are found in many marine habitats and serve as critical predators in planktonic food webs, often consuming other grazing ctenophores such as Bolinopsis infundibulum. Despite this critical relationship, comparatively little study has been conducted on the specific and complex feeding behaviors these animals display, which could expand the current understanding of the complexity in nektonic/planktonic food webs and their interactions. This study aimed to rectify this gap in the scientific literature by studying the patterns in the feeding behavior of B. abyssicola in the presence of its prey B. infundibulum, in addition to examining the impact of the prey item’s chemical cues alone on the behavior of B. abyssicola and this ctenophore’s willingness to feed on alternative prey items such as Pleurobrachia sp. We found noticeable patterns in the time spent in certain behavioral states across size ranges of B. abyssicola, with large and small ctenophores spending comparatively higher amounts of time in sedentary states compared to medium-sized ctenophores, which were much more active hunters. These relationships are likely behavioral adaptations to variations in metabolic rate and likelihood to encounter prey and suggest that these Beroid ctenophores have far more complex behaviors than widely believed. In addition, we found evidence suggesting that B. abyssicola is statistically unlikely to consume or even attack, Pleurobrachia sp. even when hungry likely due to the inability to perform such action or due to the lack of a chemical trigger.