In remote areas of northeastern Greenland, the musk ox wanders on the tundra and grazes while walking. As Arctic creatures, they need to gather enough energy to survive the cold, dark winter. Therefore, when the bright summer comes, they eat as if their lives depend on it-in fact they do.
Scientists want to know that their lives are so extreme: do they have a biological clock?
Most living things on the planet are in sync with the planet’s day and night light and dark cycles. There is a day’s eating time, a day’s sleep time, digestion time and so on. Scientists believe that the 24-hour internal clock can prevent organisms from wasting energy foraging when it may be difficult to find food during the day, thereby maximizing the organism̵
However, the long nights in the Arctic winter and the long days in the summer are very different from those in other parts of the world. Researchers reported in a paper published on Wednesday in the “Royal Society Open Science” (Royal Society Open Science) that the behavior of musk ox does not seem to follow daily routines throughout the year. The most prominent cycle of their behavior is the cycle of alternate grazing and digestion, which repeats every few hours and is sometimes discarded when not in the sun in summer.
Floris Van Best, an Arctic ecologist at Aarhus University in Denmark and author of the new paper, said that researchers used GPS collars to track 19 free-roaming musk oxen for three years. By tracking the movement of animals, they can tell whether they are eating, resting, or moving from one area to another and moving far away. Then, they check to see if there is any form in these behaviors-whether they are repeated and whether they are repeated, frequently.
Dr. Van Bister said: “We did not find a strong circadian rhythm, which means that these animals do not seem to repeat every 24 hours.
Instead, they experienced repeated foraging rounds that lasted less than 12 hours. The rhythm in winter is also very different from the rhythm in summer. Some cows disappear completely on sunny days and eat often, but eat more or less casually.
To the researchers’ surprise, whether the musk ox can maintain its rhythmic behavior in summer seems to depend on the quality of nearby food. Those in densely foraging areas did not keep up with their regularity. Those who are slim stick to their own model.
This shows that maintaining a rhythm helps to minimize the energy of the musk ox in sparse food. However, this rhythm will repeat for several hours instead of repeating once a day.
This finding coincides with an earlier study of Svalbard reindeer, in which researchers tracking animal body temperature and other measurements found that they do have a 24-hour cycle. But in summer, they ignore it completely and eat as much as possible.
Dr. Van Bister said that when it comes to musk ox, “we want to figure out the impact of this on fitness.” When some animals enter the free mode in the summer, “are they better in shape than animals that don’t?” he asks.
Now, the team is collecting information about the survival and reproduction of musk oxen to understand whether breaking through their lifestyle in the summer can make life in the Arctic region healthier and can also breed more offspring. There is more evidence that although 24-hour clocks may be normal practice, they may not be as important in every place on earth or in every animal as we think.