How old the prehistoric Leeds fish could have grown
The Leeds fish was a dinosaur-era fish species, but exactly how big it could grow is a mystery. According to an international team of researchers, the fish can grow up to 16.5 meters, making it one of the largest fish species ever recorded.
Leeds fish lived in the middle of the Jurassic Period, about 165 million years ago, and fed on plankton. In the past, archaeologists have collected many fossils of Leeds fish bones, but because these fossils are mostly smaller fragments, it is difficult to determine the exact size of this fish, and some studies have believed that its length is no more than 10 meters.
Researchers at the University of Glasgow in the United Kingdom and international colleagues have analyzed the newly discovered Leeds fish skeleton fossils, and have examined a large number of samples previously found in detail, and found that the growth structure inside its bones has the same characteristics as the rings of trees, from which its body size can be inferred.
Studies have shown that Leeds fish can grow to eight or nine metres long within 20 years of life and up to 16.5 metres in a lifespan of about 40 years. This body shape is comparable to the largest modern fish whale shark, which has a lifespan of about 70 years, so it is likely that leeds fish will grow faster than whale sharks.
Researchers say leeds fish, despite their size, feed on plankton. Its existence and extinction may be related to the dramatic changes in marine plankton populations, and studying this can help human f- understand the historical changes in marine populations.
Birds chirping
Birds' song is as characteristic as its morphological characteristics, and it has the characteristics of a species. However, compared with morphological characteristics, the song is more individual-specific, so the sound is often used to identify species and is used to identify individuals. Birds' song sounds vary greatly, some species are simple, some are complex, but they all contain different biological information. Birds of different individuals can express the behavioral communication between individuals through different sounds and different changes in sound, so as to achieve the function of communication signals, so it has the function of language - it is a special kind of "language".
Birds make sounds differently from humans, humans use their throats to make sounds, while birds rely on song tubes and song muscles to make sounds.
Birds chirping include chirping and whining. Whining refers to a variety of shorter, simpler sounds made by birds throughout the year, such as flying whining, foraging whining, nesting whining, etc. The song, on the other hand, is a longer, relatively complex song made by the male during the breeding season. The chant has two main functions: declaring the field and attracting spouses.
Bird sounds are species-specific, and different species have different sounds. Birds can recognize all-species sounds to avoid hybridization and maintain the independence of the population. Many experiments have shown that birds respond most strongly to the sounds of their species. Vocalization is a behavior of birds, which is not only related to genetic and physiological factors, but also affected by social behavior and habitat. These complex interactions contribute to the complexity and diversity of bird sounds. The formation and development of bird song is almost the same as the development of human language, and during development, chicks learn to make sounds from their fathers or neighbors, and constantly practice vocalization according to their own auditory feedback.
Birds sound like a human signature, with individual independence and individual identification. Details of the pitch, short sentence structure, syntax and composition of the song provide individual information to enable birds to recognize offspring, parents, mates and neighbors. Differences in individual vocalizations also allow birds to distinguish between neighbors and strange birds and respond. More meaningful research is based on the stability of sound, through some specific acoustic parameters to "label" individuals, or according to the differences in vocal sounds between male and female of some bird species to identify males and females, identify individuals, so as to achieve the purpose of monitoring certain populations and individuals.
The complexity of bird singing stems from the complexity of the specific structure of bird vocal organs and the coordination of the nervous system, and the expression of song singing is affected by a variety of factors at the same time, and can be adaptively adjusted according to the changed environment. From a behavioral and ecological point of view, many birds have the ability to learn to sing, resulting in the transmission of singing. Sound patterns are established by heredity and improved by experience, and the expression of their complexity is influenced by both biological and invoic factors.
In the long process of evolution, the acoustic signal adaptation of birds tends to achieve the most effective transmission effect in their respective habitats, that is, to minimize the loss of sound attenuation during transmission. In addition to the living environment, the characteristics of bird song are also closely related to the size of the bird's body and the size of the beak. Some birds will increase the frequency and sound of their songs under noise to achieve the purpose of effective communication.
Different species of birds have different song sounds, and there will be different degrees of song differences between different subspecies of the same species, between geographical populations, and even between different individuals. Differences in bird song include macrogeographic variation and microgeometric variation. Macrogeographic variation refers to distant distances, for example, acoustic variation between different geographic populations thousands of kilometers apart, and the individuals of these populations are unlikely to meet under natural conditions. Microgeormal variation refers to the sound variation between adjacent populations that are close together and have the potential to hybridize, if individuals in various groups share some or all of the vocal characteristics, and the populations are not the same and there are obvious boundaries, so that they constitute "dialects". Dialects reflect both the consistency of the sound and the individuality. Dialects can hinder population proliferation and genetic drift to some extent. The sound can also be used as a reference standard for systematic classification, especially for the identification of closely related species and sister species. The importance of bird sounds in the study of bird systematics has been widely valued.
At the end of the 20th century, bird sound studies penetrated almost every aspect of ornithological research. With the rapid development of science and technology, a variety of new types of sound recording and sound spectrum analysis equipment continue to emerge, enabling researchers to study bird song more accurately and more carefully, and greatly promoting people's analysis of the mystery of bird "language". According to the characteristics of bird sounds, modern communication equipment can be developed and improved, and can be used to attract birds, control bird pests and other applied research, in biomimicry, clinical medicine, etc., and then better serve human beings.
Why most polar bears are left-handed
Left-handed people in fauna such as orangutans and monkeys are left-handed, and the ratio of "left-handed" and "right-handed" in most animals is roughly one to one. Humans are overwhelmingly right-handed, with only 10 to 12 percent left-handed, but the vast majority of polar bears are left-handed. Why?
In addition to the genetic factors of the species, there are also some animal behavioral reasons. The phenomenon that most polar bears are left-handed is closely related to the polar bear's living environment. Polar bears are known to live on the southern edge of the Arctic with large areas of ice floes, close to the ocean, with fragments of broken ice floes and seals that breed here, and polar bears prey on seals, especially ringed seals.
Polar bears often lie next to the ventilation holes of the sea leopard on the ice surface, or creep over when the seal climbs onto the ice to rest. Polar bears have a white fur, and when it looks underwater from the ice, it will "smartly" cover its black nose with its right hand, hide itself in white, and free up its left hand to hunt, which also finds the answer to "why most polar bears are left-handed".