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Watch the "garbage fish" of the American South sucking their prey



  Video: Watch the South Dumpster Sucking Its Prey
CT scan animation of how an alligator-cook catches his prey. Picture credits: Justin B. Lemberg et al.

The Alligator Gar, a toothy, narrow-snouted fish resembling its reptile named after him, is the largest native freshwater predator in North America. They live mainly in Arkansas, Louisiana and Texas and can grow up to 1

0 feet long and 300 pounds. For a long time fishermen have referred to them as "garbage fish", which they often throw back because they are not worth the effort. Yarns have a special place in the heart of biologists involved in the development of fish.

Charles Darwin called Gars "living fossils" because they have more or less the same bodies as their Cretan ancestors more than 100 million years ago. The study of modern Gars can give many clues as to how these ancient fish and their relatives lived. Now, a new study from the University of Chicago reveals fascinating details of how the Gar nourishes by snapping his powerful jaws and surprisingly sucking his prey by sucking from the inside.

The Study of Morphology published in the Journal uses high-speed videography to take pictures of the Gar's jaw when catching this prey. Justin Lemberg, a postdoctoral fellow at UChicago who led the study, then used video footage on a 3D software model of the skull of the Gar to reconstruct the movements of his joints and bones.

"Living things These ancient features help us to understand what is going on in the fossil record," Lemberg said. "If we can figure out why some of these features are used in modern yarns, we may be able to better interpret them if these features appear in other fossils."

Overcoming the Physics of Water


Snippets from the work of researchers show how the alligator feeds Gar. Credit: Justin Lemberg / Video by Science Magazine

Unlike humans whose jaws open and close with a simple hinge, fish have complex skulls with multiple bones, joints, and cartilages that slide, bend, and rotate around the jaw to open and to extend the jaw flavor. This helps the fish to overcome a fundamental problem of physics. As they approach the food underwater, their bodies also push a wave of water in front of them. Without compensating for that, it would push him out of the way (think about how hard it is to pull a crumb out of a glass of water without holding it by the side).

Teleosts that make up most of them Nowadays, jet fish like bass or snapper solve this problem by opening their mouths, expanding the palate and parts of the skull in different places to create suction and draw water through their gills , Gars were simple "lateral snappers" approaching their prey and knocking their long snouts aside while banging their long rows of teeth down.

Lemberg used 17 alligator gars for the study, which he reared himself after picking. They were taken from a fish hatchery in Warm Springs, Georgia, and driven back to Chicago on the Honda Civic.

He then coached the Gars to feed on freeze-dried krill pieces that were held in tongs under the tongs, bright lights so he could use a special video camera that records at 500 frames per second. Surprisingly, Lviv could see that a piece of krill that was being eaten was moving into the mouth as soon as it opened its jaw, when one of the glasses was positioned on the side of the aquarium and no longer exploited its characteristic slash motion, then stay inside, when it snapped shut. That meant the gar also produced suction, just like a largemouth bass. And everything happened in just 42 milliseconds.

"It was totally unexpected to see a Gar just open his jaw and pour his food into it," Lemberg said.

  Video: Watch the garbage of Southern fish suck their prey
In a new study, a UChicago researcher has taken pictures of the Alligator's jaw as he captured prey, and used modeling to his joint – and bone movement to reconstruct. Picture credits: shutterstock.com

Lemberg also used a detailed CT scan of the skull of the Gar to reconstruct the movements of all his bones in a 3D software model. He noticed that as he watched a video showing the top of the skull, he saw white, unexposed skin flashes as the Gar closed his jaw. When he replicated this movement in the model, it appeared that part of the palate had to slide outward along a unique joint called the basipterygoide, to stretch the jaws and create the suction force.

"This suggests that only the jaws are opened" These are wide, flat plates that create a vacuum between the pines, which facilitates the collection of prey, "said Lvov." Then, when the jaws close, it expands these posterior elements to continue the suction backward rather than squeezing the prey out with the water as it squeezes. "

Love

The study complements the relatively thin literature on yarns and the mechanics of their food intake, Lemberg said the only other study specifically on Gar was published in 1980 and another that compared it to other 2004 fish.

And maybe it's time for the lower Gar to do something In March of this year, the legislature of Arkansas elected Alligator Gar a state fish after a campaign launched by a 10-year-old boy 659005] "It's definitely necessary to have this data because they can tell us as much as old fish fed," Lemberg said. "Since it was not out there, I had to pick it up myself."


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Further information:
Justin B. Lemberg et al. Feeding Cinematic and Alligator Yarn Morphology ( Atractosteus Spatula Lacépède, 1803), Journal of Morphology (2019). DOI: 10.1002 / jmor.21048

Provided by
University of Chicago




Quote :
Captured on video: Watch as the "garbage fish" of the South Sucks its prey (2019, August 20)
retrieved on August 20, 2019
from https://phys.org/news/2019-08-caught-video-trash-fish-american.html

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