Insects that "hear all directions" have different ears

Produced by: Science Popularization China

Author: Chongyan Chongyu Team

Producer: China Science Expo

If I tell you that insects also have ears, does a funny image of a tiny insect with two semicircular ears on its head appear in your mind?

In fact, insects have "ears", but unlike human ears, insect ears have various shapes and are not located in a fixed position on the body.

Perhaps what we humans imagine as "hearing in all directions" can be easily accomplished by tiny insects due to their special auditory structure!

Ears on antennae

The simplest ear is the auditory hair, which grows on the antennae. This hair-like hearing organ has a simple structure, with only one nerve cell connected to the hair follicle membrane. When the bristles are bent by air vibration or pressure, the hair follicle membrane transmits the information to the central nervous system through the nerve cells, thus making a corresponding response. The auditory hairs of male mosquitoes and ants grow on their antennae.

Ant

(Photo source: Veer Gallery)

There is another kind of "ear" on the antennae, which is also the most sensitive of all insect ears - the organ of the genus. The organ of the genus is located in the antennal peduncle. Most insects use it to control the position and movement of the antennae, but the organ of the genus of male mosquitoes and beetles is used as an organ of hearing.

Male mosquito

(Photo source: Veer Gallery)

Ears on chest

There is another type of ear called the tympanic organ, which has an elliptical or circular tympanic membrane slightly concave into the surrounding body wall, and one or more groups of scaly-tipped receptors, which are directly connected to the inner wall of the tympanic membrane or to the metamorphic membrane connected to the tympanic membrane. The tympanic organ of Lepidoptera adults is located on the metathorax or the first abdominal segment.

The moth's hearing organ is located in the concave part between the chest and abdomen. In addition to ordinary sounds, they can also sense ultrasound. This ability allows the moth to avoid being preyed upon by bats in time. When a bat appears, the ultrasound it emits has already informed the moth, so the moth quickly hides to avoid being buried in the bat's belly.

moth

(Photo source: Veer Gallery)

Ears on the abdomen

The cicada's ears grow near the second segment of the abdomen, and are composed of a relatively thick eardrum and 1,500 sword-tip receptors underneath. When sound waves reach the auditory organ and then send signals to the brain, the cicada hears the sound. However, since these sword-tip receptors are extended like silk, the sound waves they can sense are very limited, so insects that rely on sword-tip receptors to listen have very poor hearing.

cicada

(Photo source: Veer Gallery)

The ears of locusts are located on both sides of the first abdominal segment. There is a mirror-like eardrum in the small half-moon-shaped pit, and there are 60-80 sensory cells under each eardrum. However, when the locust is resting, the two ears are completely covered by the wings. Only when the wings are spread and flying, the ears are exposed and the ability to receive sounds will be more sensitive.

locust

(Photo source: Veer Gallery)

Ears on the tail

The hearing hairs of cockroaches grow on their cerci. Cockroaches are uninvited guests in your home, but the moment you spot them, they often disappear before you have time to react.

Why do cockroaches react so quickly?

In fact, the cunning cockroach can escape the moment people discover it, because the hair-like receptors on its tail give it an alarm. This kind of auditory hair is like a highly sensitive microwave vibrator, which can sense very low-frequency sound waves and can not only measure the intensity of the vibration, but also the direction.

cockroach

(Photo source: Veer Gallery)

Ears on legs

Ascaris and crickets are the most popular singing insects. Many enthusiasts do not hesitate to buy expensive and beautifully carved gourds to store these small wild insects in the grass, just to be able to enjoy their melodious and mellow singing at any time.

So how do these insects listen to each other's "songs"?

The ears they use for hearing grow on the tibia of their front legs. They are a membrane-like structure called the tympanic organ. The hearing organs of katydids and crickets are oval or slit-shaped, and there are 100-300 sensory cells in the tympanic membrane, which can quickly receive the sound signals of calling, courtship, mating, attack, alarm, etc. from the same species, and then respond.

cricket

(Photo source: Veer Gallery)

Conclusion

The ability of insects to send and receive sound signals has long attracted the attention of scientists. Now people have developed a method to control agricultural pests by using sounds of a certain frequency. This takes advantage of the ability of insects to respond to sound, attracting or repelling certain types of insects and reducing their damage in forests and fields.

Editor: Guo Yaxin