Echolocation is a method of sensory perception by which certain animals orient themselves in their environments, detect obstacles, communicate with each other, and find food .
Summary
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- 1 Origin and definition
- 2 Echolocation in bats
- 1 Sound production
- 3 Echolocation in Cetaceans
- 1 Process description
- 2 Sound production
- 3 Dolphin echolocation
- 4 Other echolocating animals
- 5 Sources
Origin and definition
Two hundred years ago, Spallanzani discovered that bats could fly in total darkness, even dodging thin, taut strings that he placed in a room. It was n’t until 1920 that someone suggested they used ultrasonic sounds , and in 1938 a Harvard student was able to hear the sounds they use for echolocation for the first time. During echolocation an animal emits a series of short, screeching sounds. These sounds travel out of the animal and then bounce off objects and surfaces in their path forming an echo .. The echo returns to the animal, giving it a notion of what is in its path.
The term echolocation refers to an ability in odontocetes that allows them to locate and discriminate objects by projecting high-frequency acoustic waves and hearing echoes. Odontocetes echolocate by making clicking sounds in order to receive and interpret the resulting echo. Acoustic waves travel through water at a speed of about 1.5 km/sec, which is 4.5 times faster than sound traveling through air .
These sound waves bounce off objects in the water and return to the dolphin as an echo. the brainit receives acoustic waves in the form of nerve impulses that retransmit the sound messages and allow the dolphin to interpret the meanings of the sound. Due to this complex echolocation system, odontocetes can determine the size, shape, speed, distance, direction, and even some of the internal structure of objects in the water. Despite the effectiveness of echolocation, studies show that a dolphin with poor eyesight takes longer to echolocate an object than a dolphin using vision in tandem with echolocation. Many details of echolocation are still not fully understood, which is why it is still under constant investigation today.
Echolocation in bats
Bats can see very well, but their vision needs some light , so they may not be able to find their prey at night with their eyes alone . They solved this problem using a sophisticated high- frequency echolocation system . By emitting a series of ultrasounds that either sweep high and low frequencies or vary around a single frequency, bats can distinguish objects and prey and thereby avoid or capture them. They can thus determine the size of an object, its shape, direction, distance and movement. The echolocation system of some bats is so precise that they can detect insects the size of a mosquitoand objects as fine as a human hair .
sound production
The bat produces a sound with its larynx (essentially the same as the human’s, but larger relative to the bat’s size) and modifies them with strange formations in its mouth and nose . When the echoes return, they reach your eardrums which change the sound into vibrations towards the bones of the inner ear and inform the brain of the received echoes. The huge ears of some bats help them catch sounds, increasing their ability to hear. Scientists are doing more research on bats using echolocation to help the blindto detect objects with the help of sound Echoes from long-eared bats are as faint as the noise of typewriter keys . Pipistrel bats make loud sounds like an alarm. Noctulid bats have the loudest sound, comparable to that of a jet engine. However, most of us cannot hear them, as these sounds are above the highest hearing threshold of our ears .
Echolocation in Cetaceans
Cetaceans , like other vertebrates and some invertebrates , such as moths (order Lepidoptera), have developed throughout their evolution a sophisticated sensory system called echolocation, consisting of the emission of sound waves in the water that the animal it ends up collecting them in the form of echoes and analyzing them in the brain. Most of the commonly called “toothed whales” (suborder Odontoceti) exhibit echolocation; mainly dolphins, killer whalesand pilot whales (family Delphinidae), porpoises (family Phocoenidae), sperm whales (family Physeteriidae), river dolphins (families: Iniidae, Platanistidae and Pontoporiidae), narwhals and belugas (family Monodontidae) and some of the so-called “baleen whales” (suborder Mysticeti), such as fin whales (family Balaenopteridae).
Process description
The sounds used in echolocation by these mammals consist of short emissions of repeated sharp “clicks” at different frequencies. Low-frequency “clicks” have high penetrating power and can travel long distances; these are reflected by structures and the animal can obtain information from the topographysurrounding. On the contrary, to locate nearby prey they emit high-frequency “clicks”, inaudible to humans. For example, the bottlenose dolphin (Tursiops truncatus), the best studied cetacean, the undisputed star of dolphinariums, is known to emit “clicks” at frequencies between 15 and 130 KHz, while the killer whale ( Orcinus orca) emits “clicks” at an average frequency of 14 KHz.
sound production
The “clicks”, whistles and “screeches” of cetaceans are produced and modulated by passing air through the respiratory tract (which in these animals is separate from the digestive tract) and associated air sacs while the spiracle remains closed . The frequency of these “clicks” is regulated by contractions and relaxations of the muscles associated with the respiratory tract and the air sacs. In captivity, it has been observed that these animals do not produce any type of loud sound because the echo produced when the waves emitted by the animal collide against the walls of the aquarium could damage their ears. The maximum frequency of echolocation clicks is about 100 KHz, but the frequency varies considerably with specific echolocation tests.
Dolphin Echolocation
The echolocation system of dolphins is considered a “sixth sense”, much more effective than sight, especially in low visibility conditions, almost exact representations of their prey can be formed, similar to those coming from sight, from the target object of your “clicks”). Dolphin echolocation is summarized as follows: When we look at an object, what we see is the light that is reflected. When dolphins “observe” an object through echolocation, what they do is listen to the sounds that it returns from the creaks or “clicks” emitted by them. Sound waves transmit much more information than light because sound has a more interactive action with the medium. wavelength produces different colors , the sound by the same system provides three-dimensional images. The texture, internal structure, and material an object is made of combine to reproduce a certain echo. It is believed that its operation is as follows: 1- The animal produces sounds internally. 2- The fatty organ of the head, the melon, focuses these sounds on a directional axis. 3- When these sounds are reflected by an obstacle, the information-carrying echoes are received in the fat-filled internal cavity of the lower jaw. When they receive a new echo, they determine at what distance and from what direction they come and more specific information such as what type of object or animal it is; predator, prey or inanimate object
Other echolocating animals
- Certain whales and dolphins. Sound travels four times faster in water than in air.
- Some shrews (small insectivorous mammals) can also echolocate.
- The guacharos or hoatzines (very primitive birds that live in caves in Venezuela), echolocate
- A cave swift (also a bird) uses clicks of its tongue to echolocate.
- A fruit bat from Egypt also uses its tongue in the same way.
