Variability of the fast suction feeding process in <i>Astatotilapia elegans</i> (Teleostei: Cichlidae): a hypothesis of peripheral feedback control

SUMMARYAlthough the motor control of feeding is presumed to be generally conserved, some fishes are capable of modulating the feeding behaviour in response to prey type and or prey size. This led to the ʻfeeding modulation hypothesisʼ, which states that rapid suction strikes are pre-programmed stereotyped events that proceed to completion once initiated regardless of sensory input. If this hypothesis holds true, successful strikes should be indistinguishable from unsuccessful strikes owing to a lack of feedback control in specialized suction feeding fishes. The hydrodynamics of suction feeding in white-spotted bamboo sharks (Chiloscyllium plagiosum) was studied in three behaviours: successful strikes, intraoral transports of prey and unsuccessful strikes. The area of the fluid velocity region around the head of feeding sharks was quantified using time-resolved digital particle image velocimetry (DPIV). The maximal size of the fluid velocity region is 56% larger in successful strikes than unsuccessful strikes (10.79 cm 2 vs 6.90 cm 2 ), but they do not differ in duration, indicating that strikes are modulated based on some aspect of the prey or simply as a result of decreased effort on the part of the predator. The hydrodynamic profiles of successful and unsuccessful strikes differ after 21 ms, a period probably too short to provide time to react through feedback control. The predator-to-prey distance is larger in missed strikes compared with successful strikes, indicating that insufficient suction is generated to compensate for the increased distance. An accuracy index distinguishes unsuccessful strikes (-0.26) from successful strikes (0.45 to 0.61). Successful strikes occur primarily between the horizontal axis of the mouth and the dorsal boundary of the ingested parcel of water, and missed prey are closer to the boundary or beyond. Suction transports are shorter in duration than suction strikes but have similar maximal fluid velocity areas to move the prey through the oropharyngeal cavity into the oesophagus (54 ms vs 67 ms).

Section: Feeding Modulation Hypothesis -Successful Vs Missed Strikescontrasting

confidence: 55%

Section: Feeding Modulation Hypothesis -Strikes Vs Transportsmentioning

confidence: 99%

Section: Feeding Modulation Hypothesis -Successful Vs Missed Strikesmentioning

confidence: 99%

See 1 more Smart Citation

Fluid dynamics of feeding behaviour in white-spotted bamboo sharks

Nauwelaerts

Wilga

Lauder

et al. 2008

“…This could explain why greater motions of the jaw and hyoid were used, as well as longer bites: if the turtles are not receiving feedback that water (or the prey item) is being pulled into the buccal cavity, then they may continue or exaggerate those movements to try to generate the expected suction. This kind of response to failed or delayed prey capture is seen in at least two species of suctionfeeding fish (Aerts, 1990;Van Wassenbergh and De Rechter, 2011). Such a response would result in longer bites with greater motions of all elements of the feeding apparatus.…”

Section: Trachemys Scriptamentioning

confidence: 99%

Terrestrial feeding in aquatic turtles: environment-dependent feeding behavior modulation and the evolution of terrestrial feeding in Emydidae

Stayton

2011

SUMMARYEvolutionary transitions between aquatic and terrestrial environments are common in vertebrate evolution. These transitions require major changes in most physiological functions, including feeding. Emydid turtles are ancestrally aquatic, with most species naturally feeding only in water, but some terrestrial species can modulate their feeding behavior appropriately for both media. In addition, many aquatic species can be induced to feed terrestrially. A comparison of feeding in both aquatic and terrestrial environments presents an excellent opportunity to investigate the evolution of terrestrial feeding from aquatic feeding, as well as a system within which to develop methods for studying major evolutionary transitions between environments. Individuals from eight species of emydid turtles (six aquatic, two terrestrial) were filmed while feeding underwater and on land. Bite kinematics were analyzed to determine whether aquatic turtles modulated their feeding behavior in a consistent and appropriate manner between environments. Aquatic turtles showed consistent changes between environments, taking longer bites and using more extensive motions of the jaw and hyoid when feeding on land. However, these motions differ from those shown by species that naturally feed in both environments and mostly do not seem to be appropriate for terrestrial feeding. For example, more extensive motions of the hyoid are only effective during underwater suction feeding. Emydids evolving to feed on land probably would have needed to evolve or learn to overcome many, but not all, aspects of the intrinsic emydid response to terrestrial feeding. Studies that investigate major evolutionary transitions must determine what responses to the new environment are shown by naïve individuals in order to fully understand the evolutionary patterns and processes associated with these transitions. Supplementary material available online at

“…This assumption does not necessarily apply to occasional, explosive movements such as suction feeding. Furthermore, the mechanical energy or work required for a single suction feeding cycle (which only takes fractions of a second to be completed) is very low compared with the energetic content of prey (Aerts, 1990). For example, if we assume that the total work for buccal expansion in C. gariepinus equals twice the work calculated by our model from start to maximum gape, total work is about 0.0034·J for the smallest and 0.3·J for the largest individuals used in this study.…”

Section: F) Scaling Of Catfish Prey-capture Kinematicsmentioning

confidence: 99%

Scaling of suction-feeding kinematics and dynamics in the African catfish,Clarias gariepinus

Wassenbergh

Aerts

Herrel

2005

Self Cite

SUMMARY Scaling effects on the kinematics of suction feeding in fish remain poorly understood, at least partly because of the inconsistency of the results of the existing experimental studies. Suction feeding is mechanically distinct from most other type of movements in that negative pressure inside the buccal cavity is thought to be the most important speed-limiting factor during suction. However, how buccal pressure changes with size and how this influences the speed of buccal expansion is unknown. In this paper, the effects of changes in body size on kinematics of suction feeding are studied in the catfish Clarias gariepinus. Video recordings of prey-capturing C. gariepinus ranging in total length from 111 to 923 mm were made,from which maximal displacements, velocities and accelerations of several elements of the cranial system were determined. By modelling the observed expanding head of C. gariepinus as a series of expanding hollow elliptical cylinders, buccal pressure and power requirement for the expansive phase of prey capture were calculated for an ontogenetic sequence of catfish. We found that angular velocities decrease approximately proportional with increasing cranial size, while linear velocities remain more or less constant. Although a decreasing (angular) speed of buccal expansion with increasing size could be predicted (based on calculations of power requirement and the expected mass-proportional scaling of available muscular power in C. gariepinus), the observed drop in (angular) speed during growth exceeds these predictions. The calculated muscle-mass-specific power output decreases significantly with size, suggesting a relatively lower suction effort in the larger catfish compared with the smaller catfish.