Scientists had assumed that the alligator caught even his prey by slamming his powerful, toothy jaw. According to a new study published on the pre-print site bioRxiv, the fish also produces a fast, strong suction power to suck prey into the jaw by moving the bones into the skull and shoulder. The paper is currently undergoing a peer review for the Journal of Morphology .
Alligator are the largest species in the gar family of freshwater fish and can grow up to 10 feet and 300 pounds in size. They are often referred to as "living fossils" because their first ancestors in the fossil record date back over one hundred million years to the early Cretaceous. Once referred to as "garbage fish", they are found mainly in the southern United States (Arkansas, Louisiana, Texas) along the Gulf of Mexico.
Their colloquial name comes from the fact that they have a broad muzzle and long teeth the American alligator ̵
"I was interested in how these joints could move during the feeding process, and what could be the reason that the jaws can move," Lemberg said of his decision to study unusual fish species. The US Fish and Wildlife Service in Warm Springs, Georgia, donated several baby alligator yarns from a batch they had bred for eventual reintroduction into the wild – basically the runts of the litter. Lviv drove from Georgia to Chicago as the car spun around in the backseat of his Honda Civic.
Back in the lab, he and his colleagues picked up the young goiter, which used freeze-dried krill on a high-speed camera to record the biomechanics of its jaws. Then they scanned a Gar Fish head to develop a high-resolution 3D model of his skull. Lemberg used this model to create a better visualization of movements of the jawbone during feeding. "I'm a very visual learner, so I made a lot of models, figures and animations," Lemberg said.
The double row of teeth of the alligator garg along the upper jaw is well suited for hunting smaller fish, water fowl, frogs, small mammals, and occasional fishing by accident. "Everything they can catch and swallow safely, they will eat," Lemberg said. Typically, alligator yarns float beneath the surface of the water, waiting for something delicious to whiz past, then jump forward quickly with a side blow to spear their prey. Feeding attacks occur within just 42 milliseconds (less than a tenth of a half second).
As the physicist Nicole Sharp explains on the FYFD: "Hydrodynamically this is a difficult way to have dinner When the Garg's mouth accelerates to its prey, it pushes a bow wave like an early warning signal To counteract disadvantage, the Garling has a complex bone structure in the skull that helps it create suction, each expansion sucks in water, and if timed correctly, the gargle absorbs throughout its attack both are already sucked into the mouth of the gar. "
Fish generally have fairly movable skulls to Lvov – a feature known as skull kinesis. This allows them to move their upper and lower jaws and their gills and gill covers. In particular, the palate moves relative to the brain housing and pushes outwards to stretch the skull and suck water. This movement is controlled by a small bone referred to as hyomandibular (19459008) (the same bone as the human stapes in the inner ear). Since Alligator Gars have a very flat palate, it was assumed that they can not turn them very much. Any upward rotation would simply bump against the skull instead of extending it.
But Lviv and others . discovered that this is not the case. Rather, the jaw of the alligator goiter moves laterally to expand the skull. "We show that they are capable of turning [their palates] it's just on a different level than what people expected," Lemberg said. "They are able to push their palate sideways outward as they pounce on their prey, and they have specialized overlapping joints that disengage."
The next step is to take over what they have learned about the biomechanics of feeding modern alligator gars and apply that knowledge to the fossil record. That is, "Gars are really useful for the ancestral traits they keep, but they are very interesting in and of themselves," said Lviv.