Currently, there are three categories of flying creatures. Bats are the only mammals capable of flight. The Malayan giant flying fox is the largest bat in the world, measuring 25 cm in length and two wings. . It measures 183 centimeters wide when opened; insects have never been large. The largest flying insect in history, the giant dragonfly, has an average wingspan of about 0.65 meters.
And the birds are not big. The largest flying bird in the world today is the great bustard, which is 110 cm long, 60 to 90 cm high, has a wingspan of 230 to 275 cm and weighs 12.4 kg.
The Wandering Albatross is the largest albatross and has the longest wingspan among many birds, with an average wingspan of 3.1 m and a maximum length of 3.7 m. However, its length is approximately 1.35 meters. Females are generally slightly smaller than males and their weight ist generally 6 to 12 kilograms. It can be said that the size of flying creatures is not large compared to mammals and sea creatures.
Why are flying creatures generally smaller?
Flying is a very, very physical thing, so it requires extremely developed wings and pectoral muscles. The wings make up a larger proportion of the body. ; bird bones make up only 5-6% of the bird's body weight. Due to the lightness of the bones, the wings are very easy to move; there are many air sacs in the bird's body, which is very beneficial to birds. reducing weight and increasing buoyancy.
Even a bird as small as a sparrow needs bones that are as hollow as possible, a digestive system that is as short as possible, a reproductive system that generally shrinks and only expands during breeding season, etc. the weight, as well as thehealing of a large number of bones. Such methods increase body strength at the expense of body flexibility.
Flying involves high-intensity activity and requires a lightning-fast metabolism to generate enormous energy needed to maintain flight, which will have a negative impact on high body temperature.
When cells carry out a series of activities, they need enzymes to improve conversion efficiency. Reactions of biological enzymes must be carried out at an appropriate temperature, usually between 25 and 38 degrees Celsius. , the temperature The higher it is, the faster the enzyme catalyzes and the more energy it produces.
However, body temperature itself requires energy to maintain. The higher the body temperature, the more energy is required to maintain it, so organisms with higher body temperatures consume more energy.rgie.
In addition, the higher the body temperature, the easier it is to damage the body mechanism, so the body temperature of us humans is generally maintained at around 36 degrees Celsius, while as birds and other flying animals; in order to maintain their ability to fly, have a body temperature of around 40 degrees Celsius.
Although a high body temperature allows them to maintain a lightning-fast metabolism, it also means that they have to expend a huge amount of physical energy every day.
Hummingbirds, the smallest birds, have a very rapid metabolic rate, with their heartbeats exceeding 3,000 times per minute. In order to obtain a huge amount of food to maintain this metabolic rate, they must eat hundreds of flowers. every day. .
Birds must constantly work hard to find food, devour it and digest it le as quickly as possible., so they developed a cone-shaped mouth for pecking, quickly swallowing the whole grain or a piece of food, and then storing the food in the developed culture.
Once the food has softened in the crop, it is gradually crushed by the gizzard, then gradually digested or absorbed by the rest of the digestive system. This method does not use teeth or associated systems and can significantly reduce weight.
These characteristics also dictate that flying creatures cannot have large sizes and weights, so they consume a huge amount of energy and need a large amount of food to satisfy this consumption .
Even the largest flying animal known to mankind, the aeolian pterosaur, has a wingspan of more than 11 meters and an average weight of only 250 kilograms. Totally disproportionate to body length. The raThe reason why Aeolus-sized creatures appeared is that the oxygen content in the Cretaceous was higher than today. Oxygen density can support the aerobic exercise necessary for flight in large flying creatures. Additionally, Cretaceous food was plentiful, which could satisfy. the energy that Aeolus needs.
But since then, as the environment has changed and food has decreased, large flying creatures have no survival advantage, so they have been gradually eliminated.
Evolutionary Trends in Birds
With human intervention in nature, it is becoming increasingly difficult for birds to obtain food. Coupled with the impact of global warming, why is the global climate degraded. Heat also affects the body size of birds. There is an opinion in the biological community that animals living in areasCold areas are generally larger, while animals living in warm areas are generally smaller. Contains heat more effectively.
A new study from Macquarie University in Australia shows that many bird species have gradually become smaller over the course of evolution.
The latest report published by Macquarie University researchers in the American journal "Puffins: Advances in Ornithology" highlights that extreme heat can have a greater impact on the size of birds than low temperatures . Chicks born in warm summers are more likely to grow into smaller adults, even if they experience cold winters in the future.
This is a compromise made by flying creatures for survival and environmental changes.