New insights from serranid fishes on the role of trade-offs in suction feeding diversification

Abstract

SUMMARYSuction feeding is central to prey capture in the vast majority of ray-finned fishes and has been well studied from a detailed, mechanistic perspective. Several major trade-offs are thought to have shaped the diversification of suction-feeding morphology and behavior, and have become well established in the literature. We revisited several of these expectations in a study of prey capture morphology and kinematics in 30 species of serranid fishes, a large, ecologically variable group that exhibits diverse combinations of suction and forward locomotion. We find that: (1) diversity among species in the morphological potential to generate suction changes drastically across the range of attack speeds that species use, with all species that use high-speed attacks having low capacity to generate suction, whereas slow-speed attackers exhibit the full range of suction abilities (this pattern indicates a more complex ʻram-suction continuumʼ than previously recognized); (2) there is no trade-off between the mechanical advantage of the lower jaw opening lever and the speed of jaw depression, revealing that this simple interpretation of lever mechanics fails to predict kinematic diversity; (3) high-speed attackers show increased cranial excursions, potentially to compensate for a decrease in accuracy; (4) the amount of jaw protrusion is positively related to attack speed, but not suction capacity; and (5) a principal component analysis revealed three significant multivariate axes of kinematic variation among species. Two of the three axes were correlated with the morphological potential to generate suction, indicating important but complex relationships between kinematics and suction potential. These results are consistent with other recent studies that show that trade-offs derived from simple biomechanical models may be less of a constraint on the evolutionary diversification of fish feeding systems than previously thought. Supplementary material available online at

Body ram, not suction, is the primary axis of suction feeding diversity in spiny-rayed fishes

“…Body ram and jaw ram can be used in combination with suction to decrease the distance between predator and prey. The amount of body ram also influences initial predator-prey distance, strike speed and strike duration, as well as the shape and volume of ingested water during the strike (Weihs, 1980;Harper et al, 1991;Higham et al, 2005;Tran et al, 2010;Oufiero et al, 2012). Jaw protrusion is the most common mechanism of jaw ram and has been shown to decrease the hydrodynamic disturbance detectable by prey while significantly increasing the suction forces on prey (Holzman et al, 2008;Holzman and Wainwright, 2009;Staab et al, 2012).…”

“…The limited reach of suction has been found to lead to very little diversity in suction distance (Wainwright et al, 2001), while there is much more variation possible in ram distance (Ferry et al, 2001b;Wainwright et al, 2001;Tran et al, 2010). Instead of a straightforward continuum between ram speed and suction capacity, the diversity of suction capacity was found to be dependent on attack speed among 30 serranid species (Oufiero et al, 2012). Others have recently focused on the duration of suction and predatory movements during feeding strikes in ray-finned fishes and found that the majority of variation among strikes is driven by the duration of ram movement (Ferry et al, 2015).…”

“…Although jaw ram is part of the suction-feeding paradigm in acanthomorph fishes (Motta, 1984), most comparative analyses focus on jaw ram's relationship to suction or how jaw ram contributes to overall ram (Norton and Brainerd, 1993;Wainwright et al, 2001;Oufiero et al, 2012). However, the kinematics of jaw ram are morphologically independent from those of body ram (fish can protrude their jaw without swimming), and therefore jaw ram provides an independent axis on which fish can diversify their preycapture strategies.…”

Automated detection of feeding strikes by larval fish using continuous high-speed digital video: a novel method to extract quantitative data from fast, sparse kinematic events

“…A very similar case is the development of a crack in solid surfaces in response to stress (Matsuyama et al, 2010), which is a highly nonlinear and unpredictable physical process that should benefit from an automatic marking of the events for the consequent analysis of, for instance, initial crack size, its location and its speed of propagation. High-speed cameras are a common tool in the study of feeding kinematics (Ferry-Graham et al, 2002;Oufiero et al, 2012;Wainwright and Bellwood, 2002;Wainwright et al, 2007Wainwright et al, , 2001Westphal and O'Malley, 2013); they are often used to record short videos (lasting a few seconds) and the analysis is usually focused on feeding kinematics and prey response. Here, we use a digital videorecording system that is geared to collect continuous high-speed videos and facilitate the unbiased identification and isolation of behavioral events in the field of view.…”

Insight into biting diversity to capture benthic prey in damselfishes (Pomacentridae)

“…A vast majority of ray-finned fishes use suction to capture elusive or loosely attached prey (Case et al, 2008;Ferry-Graham et al, 2001;Norton and Brainerd, 1993;Oufiero et al, 2012;Van Wassenbergh and De Rechter, 2011;Wainwright et al, 2007Wainwright et al, , 2001; Waltzek and Wainwright, 2003). Despite the diversity of fishes using this feeding mode, the movements leading to suction are highly conserved in teleosts (Lauder, 1985(Lauder, , 1982Sanford and Wainwright, 2002;Westneat and Wainwright, 1989).…”