Prey capture kinematics and four-bar linkages in the bay pipefish, Syngnathus leptorhynchus

Suction-feeding fishes exhibit diverse prey-capture strategies that vary in their relative use of suction and predator approach (ram), which is often referred to as the ram-suction continuum. Previous research has found that ram varies more than suction distance among species, such that ram accounts for most differences in prey-capture behaviors. To determine whether these findings hold at broad evolutionary scales, we collected high-speed videos of 40 species of spiny-rayed fishes (Acanthomorpha) feeding on live prey. For each strike, we calculated the contributions of suction, body ram (swimming) and jaw ram (mouth movement relative to the body) to closing the distance between predator and prey. We confirm that the contribution of suction distance is limited even in this phylogenetically and ecologically broad sample of species, with the extreme suction area of prey-capture space conspicuously unoccupied. Instead of a continuum from suction to ram, we find that variation in body ram is the major factor underlying the diversity of prey-capture strategies among suction-feeding fishes. Independent measurement of the contribution of jaw ram revealed that it is an important component of diversity among spiny-rayed fishes, with a number of ecomorphologies relying heavily on jaw ram, including pivot feeding in syngnathiforms, extreme jaw protruders and benthic sit-and-wait ambush predators. A combination of morphological and behavioral innovations has allowed fish to invade the extreme jaw ram area of prey-capture space. We caution that while two-species comparisons may support a ram-suction trade-off, these patterns do not speak to broader patterns across spiny-rayed fishes.

Section: Discussionmentioning

confidence: 46%

Section: Discussionmentioning

confidence: 99%

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

Longo

McGee

Oufiero

et al. 2015

“…The continuum that spans strikes in which suction is relied upon to draw prey into the mouth and strikes in which prey are overtaken by a fast-swimming predator has been a major starting point in discussions of the diversity of fish prey-capture strategies (Norton and Brainerd, 1993;Gibb, 1997;Wainwright et al, 2001;Porter and Motta, 2004;Gibb and Ferry-Graham, 2005;Higham et al, 2005;Flammang et al, 2009;Kane and Higham, 2011). Liem (Liem, 1980) initially identified three general strategies, 'ram' feeders that use high attack speed, suction feeders and manipulators.…”

Section: Suction Index and Attack Speedmentioning

confidence: 99%

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

Oufiero

Holzman

Young

et al. 2012

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

“…Members of the seahorse and pipefish family Syngnathidae, however, produce cranial elevations during feeding that far exceed those measured during sound production in Forcipiger (Van Wassenbergh et al, 2008;Flammang et al, 2009;Roos et al, 2009). The relationship between suction feeding in fishes such as largemouth bass may be explained by both cranial kinematics (Svanbäck et al, 2002) and motor patterns of associated muscles (Grubrich and Wainwright, 1997).…”

Section: Discussionmentioning

confidence: 93%

Sound production in the longnose butterflyfishes (genusForcipiger): cranial kinematics, muscle activity and honest signals

Boyle

Tricas

2011

SUMMARYMany teleost fishes produce sounds for social communication with mechanisms that do not involve swim bladder musculature. Such sounds may reflect physical attributes of the sound-production mechanism, be constrained by body size and therefore control signal reliability during agonistic behaviors. We examined kinematics of the cranium, median fins and caudal peduncle during sound production in two territorial chaetodontid butterflyfish sister species: forcepsfish (Forcipiger flavissimus) and longnose butterflyfish (F. longirostris). During intraspecific agonistic encounters, both species emit a single pulse sound that precedes rapid cranial rotation at velocities and accelerations that exceed those of prey strikes by many ram-and suction-feeding fishes. Electromyography showed that onsets of activity for anterior epaxialis, sternohyoideus, A1 and A2 adductor mandibulae muscles and sound emission are coincident but precede cranial elevation. Observations indicate that sound production is driven by epaxial muscle contraction whereas a ventral linkage between the head and pectoral girdle is maintained by simultaneous activity from the adductor mandibulae and sternohyoideus. Thus, the girdle, ribs and rostral swim bladder are pulled anteriorly before the head is released and rotated dorsally. Predictions of the hypothesis that acoustic signals are indicators of body size and kinematic performance were confirmed. Variation in forcepsfish sound duration and sound pressure level is explained partly by cranial elevation velocity and epaxial electromyogram duration. Body size, however, explains most variation in duration and sound pressure level. These observed associations indicate that forcepsfish sounds may be accurate indicators of size and condition that are related to resource holding potential during social encounters. Supplementary material available online at