short and fat tardigrades They are one of the smallest legged animals on Earth, and these microscopic waters carry wood like fat little babies. But most creatures as small as tardigrades don’t even have legs, so scientists recently analyzed the movements of tardigrades to better understand how they use their limbs.
Tardigrades, also known as moss pigs, have a segmented body and four pairs of legs. They ran across deep sea sediments and sandy riverbeds, rushing past them moss And mosses on the ground, running towards potential mates and food or away from predators.
Snapshots of bad tardigrades in species Hypsibius style He revealed that their movements are very similar to that of insects at about 500,000 times their size, even though they were separated by about 20 million years of evolution and belong to different phyla. The new study found that the stride patterns of insects and other arthropods (invertebrates with segmented bodies and articulated legs) changed as the animals accelerated, and that tardigrades’ stride followed the same pattern when they walked faster.
Related: 8 reasons why we love tardigrades
Tardigrades, of which there are about 1,300 known species, are notorious for being difficult to kill. They can survive exposure to extreme temperatures, solar radiation And space emptiness. said lead author Yasmin Nerudi, an independent researcher and fellow at the Rockefeller University Center for Studies in Physics and Biology in New York City.
Most microscopic soft-bodied animals don’t have legs, so it’s also difficult to notice exactly how these tiny animals move. By analyzing the tardigrades, literally step by step, the researchers also hope to uncover clues about movement in general on a very small scale, Nerudi told Live Science.
“We’ve seen tardigrades give us this niche in two ways we don’t know much about,” Nerudi said.
Nerudi’s team saw adults in this species gaya H.It reaches 0.02 inches (0.5 mm) in length. Their eight legs are structurally similar, but the pair closest to their hind ends have less muscle than the others. Scientists report Aug. 31 in the journal that while this pair of legs plays some role in locomotion, most of the toil is shared between the other six limbs. Prosiding National Academy of Sciences (PNS).
At first, the researchers tested the tardigrades on smooth glass slides, but they found that the water bears had difficulty propelling themselves over the slippery surface. Tardigrades walk more easily if they can dig and dart with their claws. For the remainder of the experiment, the tardigrades moved on top of the gel pressing against their feet, according to the study.
Unlike large animals that can be induced to walk or run, tardigrades are too small for researchers to stimulate their movement, Nerudi said. So scientists put microscopes and cameras in the lab, let the tardigrades off… and then waited.
“You get hours and hours of shots,” Nerudi said. “And I watched it all.”
slow step
The name phylum Tardigrada (tardigrada being the only member) comes from the Latin word “tardigradus” or “slowly,” and the tardigrada in this study fits that name. When they move at a comfortable pace, they travel about half their body length per second—about 0.01 inch (0.25 mm)—and at higher speeds, they travel about two body lengths per second.
And when tardigrades shift gears between slow and fast walking, they seamlessly shift to a new gait pattern, as many arthropods do, rather than switching to a new gait—the body’s center of gravity shifts as well—as is common in animals with backbones.
When arthropods (and tardigrades) walk slowly, they lift one leg at a time. As they accelerate, they lift two legs diagonally across the body. The faster speed causes the animal to move into a new pattern in which they are three feet off the ground at a time: the front and hind legs on one side of the body, and the middle legs on the other.
“These patterns are tightly regulated by speed, they move well between five feet on the ground, four feet on the ground, and then three feet on the ground as their speed increases,” Nerudi said. In the experiment, tardigrades were shown to follow a similar pattern in which one foot is carried in the air when the other foot is on the ground.
But why do tardigrades walk like arthropods? Groups can have a common ancestor that has been linked to bots in this way. However, it’s also possible that arthropods and tardigrades independently developed this gradual pattern, after their lineages diverged, according to the study.
“That is, even though there are very different body structures, body sizes, and environments that they go through, there is something about this particular coordination scheme that is effective in all of these conditions,” Nerudi said.
Originally published in Live Science.
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