How the nose becomes longer
Dexterity, sensitivity, strength and ease of grasping are the most prominent features of an elephant's long nose. So, how did the proboscis, the ancestor of elephants, evolve their long noses?
There is a story that the crocodile pulled on the elephant's short nose and pulled hard, quickly pulling its nose into the longest nose in the world. Of course, this is just a legend, but the evolutionary history of proboscis is indeed very interesting.
The earliest ancestors of modern elephants and their relatives lived 55 million years ago, only the size of piglets, and may not have grown a long nose at that time, but some species had flexible upper lips, very similar to today's tapirs.
Over the next geological period, proboscisivities grew larger, taller and taller, with their heads moving farther and farther from the ground. The process of natural selection favored these early proboscisians, whose skulls evolved to be larger, their bodies more specialized, and their jawbones gradually elongated to reach food on the ground. The ancestors of some elephants had jawbones that were both long and wide, and a pair of thick fangs grew.
The jawbones of proboscis animals are getting longer and longer, a process that lasts millions of years until their length and weight affect the flexibility of their movements. With its slender head, long fangs, and shorter nose, the elephant's center of gravity moves forward. In order to keep the skulls vertical, they consume a lot of energy. To escape this restriction, they must make their heads shorter, especially their jaws, but this creates a problem: tall elephants can neither reach the leaves of tall trees nor eat the grass on the ground. Natural selection thus provides a solution to the problem. Over many generations of evolution, elephants' heads and jaws have become shorter and shorter, and their noses, which are attached to their upper lips, have become longer and more flexible. The genealogy of proboscis clearly shows that the early species of this animal had a relatively short nose, while later representative species showed a more slender, developed nose.
Fossilized stone caps of proboscis animals suggest that the noses of elephant ancestors were very close in length and structure to those of modern elephants about 7 million years ago.
The role of the nose
The elephant's nose begins to develop in the womb. Elephants gestation period is 18-22 months, and in the early stages of pregnancy, the elephant's nose is separated from the upper lip margin. As development continues, the nose joins the lips and begins to grow longer. Compared with adult elephants, juvenile elephants have a shorter nose than the body in the first year of life, and juvenile elephants are not proficient in this complex organ. Sometimes, you can see baby elephants accidentally stepping on their noses and then lifting their noses into the air, writhing in pain. Elephant trunks have many uses, but they need to be practiced to use them flexibly.
The elephant's trunk can be used to reach objects overhead, even things that the elephant can't see, and its telescopic ability and flexibility allow the elephant to easily reach a variety of plants, and its feeding range is far beyond other animals. Elephants can stand upright on their hind legs and extend their snouts to reach young leaves 20 feet (1 foot = 30.48 cm) above the ground. However, elephant trunks are used for much more than just food.
The elephant nose is a combination of the upper lip and the nose, and a pair of nostrils are like two parallel snake tubes from the base of the nose down to the tip of the nose. Mouth when eating. The nostrils do most of the breathing work. The elephant's nose is also a sensitive olfactory organ. There are seven nosecarp bones in the nasal cavity (dogs have only five turbinate bones), and the turbinate bones are born with extremely sensitive sensory tissue dedicated to smelling. One of the roles of the turbinate bone is to detect hormones. When the female enters estrus, or the male enters a state of rage (serum testosterone is rising), the elephant can detect the sex hormones of its partner, chemical molecules emitted from urine and feces, and chemical signals from the elephant's nose, elephant mouth, and male estrus glands. When airborne chemical signals carry dangerous information, the alert elephant raises and rotates its nose to look like a periscope.
One of the basic functions of the elephant's nose is to absorb water. When an elephant wants to drink water, it uses its nose to suck the water into the nasal tube and then deliver it to its mouth. The elephant trunk can also be used as a retractable shower head, where elephants spray water onto their backs. Sometimes elephants also use their noses to spray dust or grass clippings on their bodies to stop mosquito bites and ultraviolet radiation.
How much water can an elephant hold in its nose? To answer this question, scientists did an experiment. They selected three elephants as subjects for experimentation. "Tommy" is a 37-year-old Asian male elephant weighing 9800 pounds (1 pound = 0.454 kg) and has not drunk water for 12 hours. In less than 5 minutes, it drank 56 gallons of water (1 gallon = 4.546 liters) and the maximum water intake per nose was 2.7 gallons. Another Asian female elephant named Zola drank 16 gallons of water in 83 seconds, about 1 gallon at a time. The third subject, "Churchill," was a baby African female elephant who drank 8.5 gallons of water in less than two minutes, less than gallons at a time.
The tip of the nose is the most sensitive part of the elephant, like the elephant's "hand", which can do the most complex and exquisite work, and its sensitivity is no less than that of a human finger. In a zoo, an elephant named "Swe" can pick up a straw of wheat that is not much thicker than a needle, and even grab a coin from the cement floor.
When two elephants meet, one will touch the cheek of the other with its nose or wrap its noses around each other. This "nose shaking" behavior is equivalent to human handshake etiquette, and has the same effect as human handshake behavior, used to greet and reassure each other. Nose gripping may also be a way for elephants to test each other's strength.
Sometimes, elephants use the lower part of their nose to hit hard ground, tree trunks, or their own bodies and teeth, producing a variety of different tapping sounds. Scientists speculate that elephants may have done this because the sound produced by tapping a hard object with their noses is much less energy than the sound produced by exhalation, which can play a role in saving energy, which is conducive to the survival of elephants. Elephants can even use their noses to mimic the tapping sound of humans. In a zoo in Portland, USA, there is a female elephant named "Bill", who can use her nose to knock on her body or concrete walls, and imitate the sound of people knocking on the door. It often fools new animal stewards in this way. After the animal steward saw through its ruse, whenever it did it again, he rewarded it with fruit, and as a result, he honed this ghost trick to the point of pure fire, and later invented a variety of imitation sounds.
Elephants' noses can also be used for self-defense and attack. Elephants are often seen chasing other animals with their noses in the wild. Males do this primarily to maintain a distance from other animals, while females do so to protect their cubs.
Thousands of years ago, people began to use the power and dexterity of the elephant's nose to engage in warfare and all kinds of heavy physical labor. Since the advent of Indian civilization, Asian elephants have been used as a weight-bearing tool, and to this day, they are still used by people for timber harvesting activities. The elephant nose and ivory of adult male elephants can carry objects weighing about 6,000 pounds and can haul wood in areas inaccessible by vehicles. If they were towed, an adult Asian elephant could tow up to 9,000 pounds of wood.
African elephants can do similar jobs, although they are not as widely used as Asian elephants.
Unusual physiological characteristics
Elephants have no bones in their noses and are made up of hair, skin, connecting tissue, fat, blood, lymphatic vessels, and muscle and nerve tissues that together weigh more than 300 pounds. The trigeminal nerve originating in the brain is divided into three branches: the eye branch, the jaw part branch, and the maxillary branch. The maxillary branches pass through the infraorbital canal into the elephant nose, where they are connected to the branches of the facial nerves. The tip of the nose is most abundant in the nerve tissue, so this part is also the most sensitive.
Think of the elephant trunk as a long cone with a nostril in the middle that extends all the way to the tip of the nose. The elephant nose is mainly composed of two large pieces of muscle tissue, the outer muscle group and the inner muscle group. The outer muscle group consists mainly of four pieces of muscular tissue: one covering the top and sides of the elephant's trunk, one wrapped under the elephant's trunk, and the other two on either side of the base of the elephant's snout. The inner muscle group is a complex network of muscles consisting of radiated and transverse muscle bundles.
From a cross-section, each nasal cavity can be imagined as half a bicycle wheel with spokes. "Spokes" are equivalent to radiative muscle bundles, and some radiative muscle bundles are anastomulated with external muscle tissue. Thousands of muscle bundles, along with external muscles, help the elephant adjust the movement of the nose, allowing the elephant to perform many delicate tasks such as picking up a peanut, fracturing it, blowing off the shell, and finally feeding the nuts into the mouth.
The skull of an elephant, made up of skulls, jaws, fangs and other teeth, is smaller than other partial bones, but if compared horizontally, the elephant's skull is definitely the largest among today's land mammals.
The skull is made up of a bone hive lattice, a structure that protects the elephant's brain tissue from extreme weather and bodily damage, while providing a light and wide surface for the connection of the trunk muscles, especially around the orifices where the nose grows. Even so, the elephant's head, along with its nose, fangs and other soft tissues, weighed more than 500 pounds. Due to the forward weight, in order to maintain balance, the elephant's neck is born shorter, its tendon tissue is as thick as a human's forearm, and its role is like a cable of a suspension bridge, connecting the head tightly to the protruding bone protrusions above the spine.
Unique sensory organs
Elephants make sounds through their throats, but when air passes through their nostrils, elephants can produce a variety of different sounds by adjusting the size of their nostrils. Elephants even have their own unique vocalization methods. Studies have found that the sound of African elephants (measured in hertz or sound wave frequency) is composed of low-frequency sound of 5 to 28 Hz and high-frequency sound of 357 to 570 Hz.
In 1984, biologist Catherine Payne discovered that elephants can communicate with each other using infrasound waves that humans cannot hear. Payne was originally inspired by the study of a small insect called the plant jumping insect, which can sing a melodious and beautiful song by vibrating its abdominal cavity, causing the leaves on the ground to vibrate, which in turn caused all the nearby plant jumping insects to join the chorus. She found that while other plant jumpers were singing, plant jumpers that inhabited peanut fields would raise one or both legs. So she speculated that this might be done so that she could hear more clearly, because the legs that were not lifted would bear more body weight and thus feel the vibrations from the ground more sensitively. A few years later, Payne discovered the same phenomenon in namibian elephant herds. She noticed that a herd of elephants that was grazing had suddenly stopped, and many of the elephants had lifted one hind leg up, one with its front leg outstretched, and cocked its toes as if they were expecting something, and sure enough, a few minutes later another herd of elephants appeared. She thinks it's the same behavior as plant jumpers.
In 1984, Payne visited a zoo. As she walked to the edge of the elephant enclosure, she suddenly felt a tremor like thunder and lightning rumble through her feet. She noticed that the forehead area between the eyes of an elephant was pulsating. Later, she used electronic devices to detect infrasound pulse waves from wild and captive elephants, eventually confirming her hypothesis that elephants could indeed communicate with low-frequency sounds that the human ear could not hear. The lowest frequency of infrasound emitted by elephants is 5 to 24 Hz. In general, the human ear can only hear sounds above 50 hertz.
Payne believes that as a communication medium, the elephant's infrasonic signal has the unparalleled advantages of many other means of communication. First, this signal lasts longer than the signal that travels through the air; second, the signal is not disturbed by weather and temperature; and again, the signal is not drowned out by leaves in the dense forest.
Elephants receive infrasonic signals through the soles of their feet and the tip of their noses. When the infrasonic signal reaches the elephant's feet, its palm first feels the vibration of the ground, and then the shock wave signal is transmitted through its bones to its inner ear, a conduction process called "bone conduction". Other organs on the elephant's body structure actually have the same function, such as the thick layer of fat on the elephant's cheek that acts as a megaphone, amplifying the received shock wave signal. The fat layer of marine mammals also has the same function, which is called "auditory fat" by scientists.
Payne believes that the tip of an elephant's nose may be more sensitive to signals from the ground than the soles of its feet. The tip of the elephant's nose is rich in nerve endings specifically designed to detect weak movements and vibrations. Biologist Stamford believes that when an elephant receives infrasonic signals, the tip of its nose touches the ground, and the tip of its nose acts as a loudspeaker.