Pursuing a live meal means you have to be quick on the draw. Which is why many fish feed by explosive mouth expansion, drawing the hapless victim into their mouths and beyond. Andrew Carroll explains that suction feeding is widespread, and while some species have small mouths and others large, no one had successfully modelled the relationship between mouth morphology and the suction pressures generated by a hungry teleost. Curious to know how fish's feeding performance varies as a function of morphology, Carroll and a team of scientists from California and Florida designed a model based on four head morphological measurements (p. 3873). But how would the model compare to real pressure measurements,straight from the fish's mouth?
Choosing five species of centrarchid fish, the team tempted famished fish while measuring the pressure in their mouths as they gulped down food. The results were surprisingly good, with the measured minimum pressures agreeing well with the values predicted by the team's model; the team reports that`epaxial musculoskeletal morphology limits suction pressure capacity'.
The team also found direct tradeoffs between morphology and the size of a fish's swallow. For example, fish that feed on large prey need large mouths,which limits the pressure they can generate. However, they may compensate for their poorer performance in other ways, by lunging at passing mouthfuls,rather than sucking them in.