Catching Prey

The skinny, freshwater alligator gar can grow to more than 2 meters in length, giving it a distinct resemblance to its namesake. But this fish’s history traces back more than a hundred million years to the Early Cretaceous. And a new (pre-printed) study, combining live observations and numerical models built from CT-scans, is shedding new light on how the gar and its prehistoric ancestors feed.

The gar uses a lateral strike (top) to come at its prey from the side. But hydrodynamically speaking, that’s a tough way to catch dinner. As soon as the gar’s snout accelerates toward its prey, it pushes a bow wave ahead of it, like an early warning signal. To counter that disadvantage, the gar has a complex bone structure in its skull (bottom) that helps it generate suction. Note how the gar’s jaw and throat open sequentially from front to back. Each expansion sucks in water, and by timing them just right, the gar produces suction throughout its entire attack. The bow wave warning does its prey no good if both are already getting sucked into the gar’s mouth! (Image and research credit: J. Lemberg et al., bioRxiv pre-print; via Science; submitted by Kam-Yung Soh)

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