Scientists had assumed the alligator gar catches its prey simply by slamming its powerful, tooth-y jaws shut. But according to a new study posted to the pre-print site bioRxiv, the fish also creates a fast, powerful suction force to suck prey into its jaws by moving the bones in its skull and shoulder. The paper is currently undergoing peer review for the Journal of Morphology.
Alligator gar are the largest species in the gar family of freshwater fish, and they can grow as large as 10 feet and 300 pounds. They are often dubbed "living fossils" because their earliest ancestors in the fossil record date back over one hundred million years to the Early Cretaceous period. Once considered a "trash fish," they are primarily found in the southern US (Arkansas, Louisiana, Texas) along the Gulf of Mexico.
They get their colloquial name from the fact that they share a broad snout and long teeth with the American alligator—most other gar have long slender snouts. Because of this, it was assumed that the alligator gar used a similar lateral snap of the jaw for feeding, but according to lead author Justin Lemberg of the University of Chicago, the jaws of the alligator gar have a lot more joints, and hence greater mobility, than their reptile namesakes.
"I was interested in how those joints were capable of moving during the feeding process, and what might be the reason for those jaws being able to move," Lemberg said of his decision to study this unusual fish species. The US Fish and Wildlife Services in Warm Springs, Georgia, donated several baby alligator gar from a batch they'd been breeding for eventual reintroduction to the wild—basically the runts of the litter. Lemberg drove from Georgia to Chicago with the gar sloshing around in the back seat of his Honda Civic.
Baby alligator gar feeding the lab. J. Lemberg et al. Reconstructed gape cycle and feeding kinematics of Atractosteus spatula, aka the alligator gar. J. Lemberg et al. Components of the mechanism of cranial kinesis of Atractosteus spatula. 1213 Reconstructed cranial anatomy based on contrasted-enhanced CT scans. J. Lemberg et al. Fully expanded feeding apparatus detailing the hyoid constrictor sheath and underlying skeletal elements. J. Lemberg et al. Fully expanded feeding apparatus detailing axial musculature and constrictors of the mandibular arch. J. Lemberg et al.
Once back at the lab, he and his colleagues recorded the young gar feeding on freeze-dried krill using a high-speed camera to capture the biomechanics of their jaws. Then they CT scanned a gar fish head to develop a high-resolution 3D model of its skull. Lemberg used that model to help build a better visualization of how the jaw bones moved during feeding. "I'm a very visual learner, so I loved making a lot of the models and figures and animations," said Lemberg.
The alligator gar's double row of teeth along the upper jaw are well-suited to preying on smaller fish water fowl, frogs, small mammals, and the occasional bit of fishing tackle by mistake. "Anything they can capture and swallow safely, they will eat," said Lemberg. Alligator gar typically float below the water's surface waiting for something tasty to swim by, then lunge forwaRead More – Source
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