Can penguins get enough sleep if they sleep 10,000 times a day for four seconds each time? | Nature Trumpet

Welcome to the 49th issue of the Nature Trumpet column. In the past half month, we have collected the following natural news and research worth reading:

1) Picky about mosquitoes, loves to chew on frogs’ nostrils

2) Penguins sleep 10,000 times a day

3) It was so hot that the bears couldn’t sleep

4) Dolphins have grown thumbs

5) Mice pass the mirror test

6) Dung beetle feces has a new use

Mosquito eating frog nose

Some mosquitoes are quite picky eaters and only like to gnaw on frogs’ noses!

In a recently published study, researchers spent three years tracking a mosquito species called Mimomyia elegans and found that it has a special liking for frogs' nostrils. In the photos taken, mosquitoes always landed on the noses of various tree frogs and sucked blood crazily .

Frog: I gave you too much freedom | John Gould, Jose W. Valdez

The researchers were surprised at first - after all, frogs eat mosquitoes ! Mosquitoes jump back and forth on the frog's nostrils, and the frog can swallow them into its mouth with its long, sticky tongue. How is this different from plucking a tiger's whiskers?

After further observation, the researchers found that mosquitoes have a cunning strategy: they do not land directly on the frog's head (otherwise they become food delivered to the door), but first land on a part of the frog's body that it cannot see, such as the frog's back; then quietly move forward, and climb into its nostrils while the frog is not paying attention to start eating. Frogs cannot see their own nostrils, so mosquitoes can always hide in the frog's blind spot .

Mosquito: Enter the village quietly, don't shoot | Reference [1]

As for why mosquitoes like frog noses, researchers have come up with some possibilities. For example, the skin on the surface of the nostrils is very thin, and the mosquito's mouthparts can easily penetrate it; and the nose is one of the organs with the richest capillaries, so mosquitoes can suck the most blood.

Penguins sleep 10,000 times a day

Penguins sleep 10,000 times a day, but each sleep lasts only 4 seconds .

Take a nap secretly | Won Young Lee

In a new study, scientists implanted electrodes in 14 chinstrap penguins and analyzed their sleep by measuring brain wave data. The results showed that the penguins only fell asleep for an average of 4 seconds each time, which is called "microsleep." Microsleep is actually dozing off - surveillance videos show that when penguins enter microsleep, they are like drowsy students in class , and their brains can be seen to have been secretly offline from the way they nod and blink.

Listening to a lecture, really | Tamatukurikei / Wikimedia Commons

Penguins doze off thousands or even tens of thousands of times a day, which adds up to more than 11 hours of sleep a day. For us humans, if we don't have a full sleep of several hours a day and just take a nap from time to time, we always feel that we haven't rested well. However, for penguins, fragmented sleep allows them to get enough rest.

Penguin on the right: The neighbors are so noisy! | Jerzy Strzelecki / Wikimedia Commons

Why do penguins sleep like this? On the one hand, when penguins are incubating eggs and raising their children in the nest, there are always seagulls watching closely. Penguin parents can only stay alert in this half-awake and half-asleep state to protect their children. On the other hand, penguins are social animals, and there are always noisy friends around them, so there is no quiet sleeping environment . The penguins standing in the center of the flock are more likely to be disturbed because they have more neighbors next to them, just like humans can't sleep in a noisy food stall.

Bear can't sleep

Because the weather is too hot, the bears can't hibernate.

Brown bears in Russia's Amur region are in an awkward situation - they have already put on weight and made all preparations for hibernation, but the temperature has not dropped and they can't sleep. They should have gone into hibernation in October , but now, more than a month has passed, they are still wandering outside half asleep and half awake .

Brown bear | Frank Vassen / Wikimedia Commons

According to reports, the Amur region saw record high temperatures in October and November this year, which not only delayed the bears' hibernation, but also caused them to wake up earlier . A study found that for every 1°C increase in temperature, bears would end hibernation 3.5 days earlier on average. In some places where the temperature is too high and food is plentiful in winter, it is common for bears to stay awake in winter.

Brown bears living in urban areas do not hibernate in winter because they eat food from human garbage bins | sskaneko09 / Wikimedia Commons

There may be another reason why brown bears in the Amur region have not returned to their dens - because the temperature is above freezing, water from melted snow flows into their dens , and the bears are not comfortable living in leaky homes.

However, most of the brown bears still roaming around are males, while female brown bears and cubs are less affected. Cub bodies can store less energy, and their basal metabolic rate per unit body weight is higher than that of adult bears. Mother bears will pay special attention to not letting cubs consume too much calories in the preparation stage for hibernation, so hiding in caves and hibernating peacefully is the best protection.

Dolphin with thumb

What? A dolphin has grown thumbs!?

This is a striped dolphin, which was recently found in the waters near Greece. Researchers believe that this does not look like a disease, but may be a rare gene expression that happened to cause problems in the development of the dolphin's fingers.

Dolphins with "big thumbs" | Alexandros Frantzis / Pelagos Cetacean Research Institute

Yes, you read that right, it is indeed finger development - in fact, dolphins do have fingers, they are just hidden in their flippers and we can't see them.

As marine mammals, dolphins and other cetaceans are different from fish. In terms of skeletal structure, they have fingers similar to humans , but with more finger bones. When the embryo develops in the womb, the cells between our fingers will die, so we have five distinct fingers at birth and can move flexibly; however, during the embryonic stage, the cells between the fingers of dolphins do not die, but form flippers around the fingers , so the fingers cannot move. Although they no longer have five dexterous fingers, dolphins have fins that help them ride the wind and waves.

This is an X-ray of a dolphin flipper, which has a bone arrangement similar to that of human fingers, but with more phalanges. Scientists use the state of the bones here to determine the age of the dolphin (this picture is from a 58-year-old male dolphin) | Barratclough et al., 2019

This special dolphin with thumbs may have encountered an accident during its development before birth: the cells of the second and third fingers (equivalent to the human index and middle fingers) died; while the first and fourth fingers grew normally and were wrapped by the flippers, eventually growing into a unique appearance.

Mouse mirror test

The mouse passed the mirror test!

Is this me in the mirror? | References [5]

The mirror test is a classic test of animal cognition. It tests whether animals can recognize themselves in the mirror to determine whether they have the ability to self-recognize. In a new study, researchers painted white ink on the heads of black mice. Compared with mice without white markings, mice with white ink spent more time combing their heads in front of the mirror, trying to wipe off the white ink on their heads . This shows that they understand that the mouse with white ink on its head in the mirror is themselves.

The top of the black-haired mouse's head was stained with white ink | Reference [5]

However, mice had to pass the mirror test under certain conditions. First, if the ink on their heads wasn't obvious enough, such as black ink on a black-haired mouse, or if the white ink was too small, they wouldn't notice the change in their appearance.

In addition, mice need to have social experience living with their own kind in order to have mirror self-recognition . If they do not live with their own kind after weaning, or if a black-haired mouse lives in a group of white-haired mice, they will not be able to recognize themselves in the mirror - after all, only by living with a group of companions who look similar to themselves can they know what they look like.

Little Mouse: Why is my hair turning white? | References [5]

Through further research, scientists found that whenever mice recognized themselves in the mirror, some neurons in their hippocampus were activated . These neurons are responsible for the self-recognition of mice. Once scientists disabled them, the mice could not recognize themselves in the mirror and would not make the action of cleaning the ink stain.

Dung beetle shit

If you want to measure biodiversity but don’t know what mammals are in the area, what do you do? Dung beetles say: I’d rather rely on my poop.

Dung beetles feed on mammal feces and use it as a place to lay eggs and shelter their larvae. In theory, as the "poop shovelers" of mammals, dung beetles know the local mammals better than anyone else .

Moving shit | Luca.favorido / Wikimedia Commons

Recently, scientists trapped 18 dung beetles in the tropical forests of Xishuangbanna and extracted DNA from their intestines. Sure enough, they detected genetic information from eight mammals recorded in the area , including common wild boars and domestic cats. In the intestines of one dung beetle, they even found DNA from rare species, including Asian black bears, red muntjacs and northern pig-tailed macaques.

Dung Beetle: To be honest, I’ve eaten all kinds of shit! | Achiri Bitamsimli / Wikimedia Commons

With dung beetles as "intermediaries", scientists do not need to conduct in-depth surveys of the entire area and spend time tracking those elusive mammals to understand the local species distribution. Moreover, they do not need to capture new dung beetles alive every time - if the previous dung beetle samples are properly preserved, effective DNA information can still be extracted from the intestines. If a live dung beetle poops after being caught, it will lose the DNA stored in its intestines.

References

[1] https://onlinelibrary.wiley.com/doi/10.1111/eth.13424

[2] https://www.science.org/doi/10.1126/science.adh0771

[3] https://www.livescience.com/animals/bears/half-asleep-bears-are-wandering-around-siberia-because-its-too-hot-to-hibernate

[4] https://www.youtube.com/watch?v=1lUhjckyOYg

[5] https://www.cell.com/neuron/fulltext/S0896-6273(23)00803-6

[6] https://onlinelibrary.wiley.com/doi/10.1002/inc3.29

Author: Cat Tun

Editor: Mai Mai

Title image source: Won Young Lee

This article comes from GuokrNature (ID: GuokrNature)