There are no bones in the elephant's trunk, so how can it perform various complex movements?

Tuchong Creative

Elephants are very special animals. Everyone knows that they have a long trunk that no other animal has. But do you know what is so special about the elephant's trunk? How can an elephant complete various complex tasks without bones in its trunk? How are the wrinkles on the elephant's trunk formed and what is so special about them?

The ancestor of elephants is the proto-elephant that lived about 36 million years ago. If you traveled back to that era, you might mistake them for the ancestors of pigs. Because the proto-elephant not only has a short nose, but also has a body shape that is far from the elephants we are familiar with, and is more like a pig. Why did they evolve into the appearance of elephants today?

The long trunk of an elephant is actually the fusion of its upper lip and nose, which makes it longer and has the ability to grasp, allowing the elephant to put food from afar into its mouth, and can also be used to carry things or even use the long trunk to suck water into it and send it to its mouth. According to the study of the fossils of the elephant's ancestors, paleontologists have found that the ancestors of elephants lived beside rivers and lakes, in an environment with lush water and grass, and spent a long time in the water every day. In order to facilitate their breathing, their trunks gradually became longer to assist breathing; this flexible nose also has the ability to grasp, allowing the ancestors of elephants to use it to roll up distant bushes, high leaves, and grass on the ground and send them to their mouths, reducing their physical consumption when foraging. This is why elephants have evolved long trunks. However, some scholars have expressed doubts about this evolutionary process, but no matter what, elephants have relied on this long trunk to get to where they are today after a long evolutionary journey.

Why can the elephant's trunk, an appendage made entirely of muscles without bones or joints, perform a variety of tasks?

First of all, the elephant's trunk contains nearly 40,000 elastic small muscles, 150,000 muscle bundles and tens of millions of nerve endings. Each of these muscles has different roles and functions. A special nerve is pulled out from the brain specifically for controlling the trunk, allowing the elephant's brain to transmit commands through this nerve to regulate the contraction or relaxation of tens of thousands of muscles in the trunk. Under the control of the nerves, they work together to achieve various complex movements and behaviors of the trunk.

Secondly, although there are no bones, cartilages or joints in the elephant's trunk, through the coordinated action of muscles, the trunk can form joint-like structures at multiple points, which increases the flexibility of the trunk's movement. There are also many wrinkles on the trunk, which can protect the internal tissues while maintaining plasticity, allowing the trunk to perform movements such as curling. If there were no wrinkles on the skin of the elephant's trunk, the flexibility and plasticity of the trunk would be greatly reduced, and it might even become an almost immobile stick.

In addition, there are a large number of blood vessels in the trunk. By contracting and relaxing the muscles, the blood flow in the blood vessels can be controlled, and the shape, softness and hardness of the trunk can be changed. This is very similar to the principle of controlling our tongue. When the muscles contract, the blood vessels will be squeezed, the blood flow will decrease, and the trunk will become tighter and can grasp or wrap objects. When the muscles relax, the blood vessels will be dilated, and the blood flow will increase. At this time, the trunk will become soft and flexible. When the muscles are relaxed and tense, the skin on the surface of the trunk will stretch with the muscles. The existence of wrinkles on the skin allows the epidermis of the trunk to be fully stretched and tightened. When the trunk is congested, hardened and enlarged, the wrinkles ensure that the skin has good ductility. Without these wrinkles, the epidermis of the trunk will be "torn" during movement.

There are many magical things about the wrinkles on the trunk. For example, the wrinkles on the trunk are not formed gradually over time, but they are formed when the elephant is still an embryo. Biologists have found through research that their formation is caused by genetic genes and may be synchronized with the functional development of the trunk. In addition, there are differences in the number and shape of wrinkles on the noses of Asian elephants and ordinary African elephants. Asian elephants have more wrinkles on their trunks, with an average of 126, while African elephants have an average of only 83. Biologists believe that this may be related to the shape of the trunk and the habit of grasping things. There is only one protrusion at the end of the trunk of Asian elephants. When grasping objects, they are more accustomed to using one-third of the end of the trunk to wrap the objects. The wrinkle density in this area is the highest, and more wrinkles help to bend. The ordinary African elephant has two protrusions at the end of the trunk. When grasping objects, they tend to use these two protrusions to pinch, so they don’t need to bend the end of the trunk too much, and there are fewer wrinkles.

Through the study of trunk wrinkles, scientists have found that this feature has very positive practical significance in many disciplines. For example, in biology, the development of trunk wrinkles can help us understand the mechanism of wrinkle formation on the skin of elephants and other animals; in ecology, the number and function of wrinkles are closely related to the behavior of elephants, and the formation of wrinkles may be related to the living environment of elephants, which helps us understand how elephants adapt to different environments to survive and reproduce. In engineering, the structure of trunk wrinkles can provide a reference for the design of robotic arms, thereby improving the flexibility and precision of grasping. For example, the outer shell of joint parts can be improved by referring to the structure of trunk wrinkles; in the grasping arm part, the protrusion at the end of the trunk can be used as a reference to enhance the grasping accuracy, and at the same time, the number of joints in this area can be increased to improve flexibility; in materials science, the structure of trunk skin and wrinkles can provide a basis for the research and development of new materials with better ductility and higher strength.

Author: Li Weiyang Popular Science Writer

Reviewer: Zhao Xumao, Young Researcher, Lanzhou University

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.