Bats have the most beautiful and perfect sonar system in the animal world. The snout of their head has a "nasal lobe" structure surrounded by complex special skin folds. This special device has the function of transmitting ultrasonic waves. Bats have high sensitivity and resolution. Based on the echo, they can not only distinguish the direction and locate their own flight path, but also recognize different insects or obstacles, effectively dodging or chasing. They used this "echolocation" method to find very small prey of distant individuals in the dark night and catch them as fast as they could.
However, the Tao is one foot high, and the devil is one foot tall. While bats rely on echolocation in the dark to find and prey on insects, and the technique of controlling their wings to hunt insects is better than any bird, some insects also have countermeasures that can subtly escape the bat's pursuit.
One of the larger families of Lepidoptera is called Noctuidae. There are more than 20,000 species in the world. Nocturnal moths, like bats, ambush during the day and appear at night, but under natural conditions, bats rarely catch nocturnal moths. Scientists have observed the bat flying on the nocturnal moth, but before it reaches the front of the nocturnal moth, it is always felt by the moth and therefore escapes. There are also many ways for nocturnal moths to escape bat pursuit: sometimes they fold their wings and land on the ground in an emergency; sometimes they fall directly and hide motionless on the ground; sometimes they rotate horizontally and vertically, flying backwards or circling, making it impossible for the bat to start. Nocturnal moths are a larger insect. Why are bats not easy to spot, but why?
It turns out that the body of the nocturnal moth has a wonderful "ear" - the eardrum. The tympanic membrane organ is located in a recess between the thorax and abdomen of the nocturnal moth. On the outside is a layer of angular folds and eardrums. Inside there are airbags, sensors and tympanic chambers. There are two auditory cells and one non-auditory cell in the cavity, which make up its "ear". The nerve fibers here are parallel to each other, forming a bundle of tympanic nerves that connect to the main nerve trunk and lead to the thoracic ganglia. Its "ears" are very sensitive, and even if the bat is noisy, it can receive ultrasonic signals from the bat. When the bat flies to a certain distance (up to 30 meters), the eardrum organ of the nocturnal moth receives an alert for the arrival of the bat.
Some nocturnal moths also have anti-echo detection equipment for bat echo detection. In the joints of these luminous appendages, there is a vibrator that emits a series of ultrasounds as the leg muscles contract. The vibration frequency of the ultrasound is within the hearing range of the bat. Bats cannot determine the target well when they hear this ultrasonic interference signal, thus losing the ability to accurately locate under the effective interference of nocturnal moths. At the same time, a thick layer of fluff in the body of the nocturnal moth also began to "fight", absorbing the ultrasonic waves emitted by the bat and weakening the echo intensity received by the bat, thus destroying the function of the bat sonar system to a certain extent.
Some people have summed up several characteristics of the anti-sonar tactics of the nocturnal moth: one is to take the initiative to reconnoiter and understand the enemy situation in advance; the second is early warning and early defense preparation; the third is to actively interfere and confuse the natural enemy; the fourth is to absorb ultrasound and reduce the echo; and the fifth is to subtly change the strategy to escape. It is through these different forms that they escape the predation of bats and thus protect themselves.
Over the course of long-term co-evolution, the predatory pressures of bats led to the evolution of a range of traits of the nocturnal moth family and other nocturnal insects. The adaptive characteristics of insects also affect the improvement of the echo localization system of bats and their predation strategies. The evolutionary adaptation of organisms is really great.