The researchers found that from their first flight, these echolocating mammals somehow knew exactly how long it would take for the sound waves of their calls to echo from their prey. again. An innate reference point related to the speed of sound allows bats to judge distance in units of time, as opposed to spatial units like humans. Unlike humans who rely heavily on sight, various types of bats “see” the world around them with their ears. However, just as our eyes can fool ourselves, bats don’t always decode their echoes correctly. Illustration. For the test, the team housed six newborn bats in normal atmospheric conditions, as well as five newborn bats in helium-enriched air. This will increase the speed of the sound. These two groups were then tested for echolocation in their respective environments. When approaching a food target, helium-enriched airborne bats displayed echolocation patterns and normal airborne bat-like flight behavior. When a bat flies and lands somewhere, it requires precise coordination between its call to attract and its body. As the creature gets closer to its target, the bat’s echolocation speed increases, and when landing slows, it rolls its body, straightening its legs. However, in an environment where the speed of sound travels faster, this all happens much faster, causing the bats to land ahead of their target. Despite many attempts, the bats still managed to approach the target using the normal sound reference speed. The problem is that bats never learn from their mistakes. Even when adult bats were conditioned in a helium-enriched environment for several days, the researchers found that they were unable to change this fixed reference point. This is surprising, since sensory learning is an advantage for many animals, especially those with the ability to change conditions. Little known secrets about bats According to the analysis results of scientists, in the feces of bats there is a lot of potassium nitrate salt, also known as salt pepper. This chemical is the main ingredient in many fertilizers. At the same time, it is also used to make explosives and detonators. In the past, especially during the American Civil War, bat droppings were considered an important resource for both sides. Because from this waste, one can extract salt and pepper (which is quite scarce) to supply the army. When it comes to bats, most of us probably think of animals with a “unique” way of sleeping upside down. According to scientists, this unusual sleeping position of bats actually has its own purpose. Specifically, unlike birds or insects, the leathery wings of bats are not strong enough to easily lift them from the ground to the air. Therefore, when resting, bats always choose an elevated position so that when they need to fly, they just drop down, taking advantage of air resistance to support take-off. However, according to statistics, there are 6 species of bats that do not hang upside down when sleeping. Most of them have suckers on their limbs, allowing them to cling to leaves or other flat surfaces to sleep. In fact, only small bats (suborder Microchiroptera) have poor eyesight and must be located using sonar. Meanwhile, the larger representatives (of the suborder Megachiroptera) possess excellent eyesight. Even the vision of these bats is better than that of humans. However, in exchange for “bright” eyes, members of the suborder Megachiroptera do not know how to use ultrasound waves.

A baby decorated with flowers when taking pictures. Although it has faded as digital has evolved, photographing the dead was once a huge business, a means of denouncing war crimes. The origin of the trend Currently, cameras are available on mobile devices so people can store images anytime, anywhere. However in the Victorian period, cameras were not so popular and convenient. Taking personal photos is also very expensive, so many people do not have any pictures while living. Until their death, relatives have spent a large amount of money on a photo to keep memories. Especially for families with the death of a child, it becomes more spiritual to take pictures. Early photos were often blurred, but not because of the technology of the camera at the time. Victorian cameras were capable of producing sharp images but the technology was very slow. Usually, the person being photographed must sit still for at least 20 seconds, no blinking or moving limbs. Even breathing can affect image sharpness. People are under pressure to sit or stand upright in clothes that are flat. Photographing the living person at that time was extremely difficult. On the contrary, it is easier to take pictures of the dead because they do not move or breathe or ruin the photo. Amateurs looking to improve their skills and create sharp images often find dead guests. Many people have saved a few photos while living, but because the quality of photos of dead people is usually better than those of living people, families still take pictures of them after death. This photo can show sharp details and features about the deceased. When corpses take pictures with loved ones, they also become “in focus” with sharp images while the people around them may be a little blurred. Nowadays, it seems crazy to spend large sums of money to take photos of the dead. But because today, or at least in the West, death is hidden, no longer lurking around. Modern people enjoy life to the fullest and often avoid thinking about or mentioning death. Death has become a foreign thing, a horror to them. But research from the University of North Carolina, USA, shows that during the Victorian period, human life expectancy was low while mortality was high. People have to constantly watch their relatives and friends pass away. In particular, it is common for children to die when they are young. From childhood, people have become acquainted and understood about death. The art of photographing the deceased Not only taking photos, but people want the pictures of the dead to come true and vivid as if they were just taking a nap. Death is often associated with mourning, but if you look at the Victorian photographs, the reality is the opposite. Photos of the deceased are quite beautiful. Many pictures are arranged or arranged purposefully. When photographing the dead became a major business during the Victorian era, trade magazines such as Philadelphia Photographer offered advice to “assist the amateurs in creating impressive photographs of the dead”. They suggested placing the corpse near a window to take advantage of natural light. Even so, sunlight cannot bring a corpse to life. Therefore, photographers have created many ways to make shooting the dead look more natural. After the photo was printed, they used color to paint the eyes wide to help the dead look soulful. Let the dead sit upright, loved ones can take pictures with and support their backs. Normally, it takes about three people to hold the arm, lift the dead person’s head, and some people use a support to help the dead stand upright. Families also often decorate teddy bears and toys around children to create a joyful, warm space, and comfort the little souls … However, more and more people photographing was transformed and commercialized. Celebrities died have become “prey” to the wings of photographers. They secretly attend funerals to take photos of celebrities to sell to newspapers or card printing companies in exchange for large sums of money. Many people, because of their idols or curiosity, have spent money to buy these pictures. For example, the photo of a French writer, Victor Hugo, who died looking like he was sleeping, was printed in large numbers on postcards. Soldiers died in the American Civil War. Exposure to war crimes Photographing the dead isn’t just limited to the home. When photography became popular, the American civil war broke out. Photographers have another task is to take pictures of the battlefield. In it, it is indispensable to take photos of the generals and soldiers who died in different poses, but all in all are bloody, haunting moments. War is a strange thing for people living in a peaceful area, but photography has brought war closer to everyone. The sacrifices of the soldiers denounce the cruelty and the heavy damage that war brings. War photos are displayed at photo galleries, published in newspapers or as souvenirs. They have had a strong impact on people’s awareness of war crimes, and spurred movements to restore peace. The trend disappeared In the early 20th century, photographing the dead was no longer popular because of changes in society. Thanks to the development of health care, the infant and population mortality rate has sharply decreased. From the 1900s, whether old or young, when sick, they are admitted to the hospital and may die in them without relatives. This means death takes place behind closed doors, rather than in the comfortable and open spaces of the house. Furthermore, photography has become more popular. Everyone can take pictures many times by themselves, without the need for a photographer, it is no longer feasible to take a “single and last” photo. However, photographing of the dead still exists, but for more privacy or for special purposes. In the present era, it will not be easy to see pictures of the deceased even though this trend has flourished many decades ago.