09/23/2021 at 6:08 PM CEST
Researchers at the University of Michigan, in the United States, have found in a new study that the intestinal worm C. elegans is capable of detecting and responding to sounds, although it does not have specialized organs for hearing such as the ears of humans and animals. It does this from auditory sensory neurons that are closely connected to your skin.
According to a press release, research recently published in the journal Neuron allows access to a new understanding when studying the hearing sensation, even with perspectives of developing therapies and complements for people with different hearing disabilities.
The worm C. elegans It has been widely used in research in the biological field, given its surprising conditions. Despite being only a millimeter long, previous studies have shown that this species has the ability to “feel” light, although it does not have eyes. At the same time, you can perceive your own body posture during movement, a quality known as a sense of proprioception.
They also pick up sounds
However, until now it had not been possible to verify that these worms had something similar to the primary sense of hearing, or that they could process auditory sounds and sensations in some way. As the researchers explain, this has to do with certain scientifically established conceptions.
The hearing it is different from other senses such as touch or vision, which have been widely verified in other animals. In reality, the ability to perceive sounds has only been discovered in vertebrates and some arthropods. Therefore, it is believed that the vast majority of invertebrate species such as C. elegans cannot experience auditory sensations.
Once again this roundworm It has come as a surprise: after different experiments, American scientists discovered that worms responded to air sounds in the range of 100 hertz to 5 kilohertz, an even wider range than some vertebrates can feel. These ranges are “bands” in the sound spectrum that characterize sounds: some allow you to hear higher pitched sounds, others more serious or intermediate, among other possibilities.
Related topic: They create music from the vibrations of the cobwebs.
So “listen” C. elegans
According to the specialists, when a tone is reproduced in that range, the worms quickly move away from the source of the sound, showing that they not only hear the sounds but also they perceive where they come from. How do they do it without having ears or other hearing organs?
They do not actually “feel” the sound vibrations through their sense of touch, but rather their entire body functions as a kind of cochlea, referring to the fluid-filled spiral cavity that exists in the inner ear of vertebrates. At the same time, they use two types of auditory sensory neurons strongly connected to your skin.
When the sound waves collide with the skin of the worms, the liquid inside the worm produces vibrations, in the same way that the liquid vibrates in the cochlea of an ear. These vibrations activate the auditory neurons attached to the skin of the worms, eventually turning them into nerve impulses.
Because the two types of auditory neurons are located in different parts of the worm’s body, C. elegans can detect the origin of sounds and protect themselves from the attack of their predators. According to the researchers, it will now be possible to delve into the genetic mechanisms and neurobiology that drive these sensations, paving the way for new discoveries in the field of animal hearing and even its adaptation to new therapies and treatments in humans.
The nematode C. elegans senses airborne sound. Adam J. Iliff, Can Wang, Elizabeth A. Ronan, Alison E. Hake, Yuling Guo
Xia Li, Xinxing Zhang, Maohua Zheng, Jianfeng Liu, Karl Grosh, R. Keith Duncan and XZ Shawn Xu. Neuron (2021) .DOI: https: //doi.org/10.1016/j.neuron.2021.08.035
Photo: New research from the University of Michigan reveals that the roundworm C. elegans (shown above in the shape of an ear), a model species used in biological research, can sense and respond to sound waves in the air despite not having organs similar to ears. Credit: Rajani Arora, University of Michigan Life Sciences Institute.