EcholOcation
The film, Dracula certainly made Bats look fearsome and terrifying, but they hold a fascinating technique in order to locate their prey! As humans, we don’t need to hunt for our prey, but for some animals, especially the bat, they have to use echolocation to locate their prey. It should be noted that echolocation does apply to other animals such as the dolphin, not just the bat only.
When a bat is hungry, it uses its skill of echolocation to hunt its prey. The fruit bat tends not to use echolocation, instead it uses its sight and smell; “Most fruit bats use eyesight and smell for finding food not echolocation” (National Parks, n.d). The bat is able to emit a sound wave, with successive gaps in between each release of a sound. These sound waves travel out and will hit objects and reflect back to the bat, or it will not reflect at all as there are no objects within the vicinity. The location of where the sound waves are released from the bat varies, but the two possible places are “though their nose but most bats use their mouth” (National Parks, n.d). The returning reflection from the prey, if any reflection at all, is assessed by the bat and it models the surroundings within the brain. A returning reflection is known as an echo, which is why this technique includes echo within its name. Above is an image, which visualises the theory. A sound wave is sent out from the bat, yellow in the diagram and the reflection, purple, is returned back to the bat. An impressive fact that goes to show how remarkably clever bats are suggests that “Bats give off pulses at very high frequencies that are not audible to humans, at an impressive rate of 200 pulses per second” (University of Hawaii, n.d).
When a bat is hungry, it uses its skill of echolocation to hunt its prey. The fruit bat tends not to use echolocation, instead it uses its sight and smell; “Most fruit bats use eyesight and smell for finding food not echolocation” (National Parks, n.d). The bat is able to emit a sound wave, with successive gaps in between each release of a sound. These sound waves travel out and will hit objects and reflect back to the bat, or it will not reflect at all as there are no objects within the vicinity. The location of where the sound waves are released from the bat varies, but the two possible places are “though their nose but most bats use their mouth” (National Parks, n.d). The returning reflection from the prey, if any reflection at all, is assessed by the bat and it models the surroundings within the brain. A returning reflection is known as an echo, which is why this technique includes echo within its name. Above is an image, which visualises the theory. A sound wave is sent out from the bat, yellow in the diagram and the reflection, purple, is returned back to the bat. An impressive fact that goes to show how remarkably clever bats are suggests that “Bats give off pulses at very high frequencies that are not audible to humans, at an impressive rate of 200 pulses per second” (University of Hawaii, n.d).
The video above shows how the input and output sound waves interact when hunting for prey.
As with all living creatures on planet Earth, evolution plays a major role in some of the bats prey. A typical diet for a bat involves moths, crickets and many other small insects. The prey is able to listen to the sound waves from bats, which in turn allows for a game of cat and mouse. As the insects interpret the sound waves, they will try to dodge and move so it can survive.
The way, in which humans have evolved, has hindered us unable to listen to the high frequencies that bats are able to produce. This is down to the way the human ear is shaped as the pinna is fixed into position and there is no muscle control over it. Bats are able to move their pinna into the ear canal, which is then consequently released. This happens as they have a muscle within their pinna to move it in and out. The motion of the pinna is positioned into the in position (covering the ear canal), the bat releases a high-pitched frequency and the pinna moves back out to listen to the echo that is reflected. As previously mentioned the bat can release 200 pulses a second, so the pinna is moving in and out extremely quickly to pick up the reflecting echoes. The processing power of a bats brain means it can quickly perform calculations within milliseconds to help locate its prey. For example, if we assumed that the frequencies are travelling at 340 metres/second and the prey is stationary and the time it takes for the echo to bounce back into the bats ears is 0.3 milliseconds; then the distance of the prey is 0.102 metres. This simple calculation was performed by multiplying the speed of sound by the time it takes for an echo to reflect into the bats ears. This process is constantly occurring when a bat is hunting for food, which makes them a fascinating creature to study! This is a very simple mathematical calculation, however it is not as simple as this, as shown in the image below.
As with all living creatures on planet Earth, evolution plays a major role in some of the bats prey. A typical diet for a bat involves moths, crickets and many other small insects. The prey is able to listen to the sound waves from bats, which in turn allows for a game of cat and mouse. As the insects interpret the sound waves, they will try to dodge and move so it can survive.
The way, in which humans have evolved, has hindered us unable to listen to the high frequencies that bats are able to produce. This is down to the way the human ear is shaped as the pinna is fixed into position and there is no muscle control over it. Bats are able to move their pinna into the ear canal, which is then consequently released. This happens as they have a muscle within their pinna to move it in and out. The motion of the pinna is positioned into the in position (covering the ear canal), the bat releases a high-pitched frequency and the pinna moves back out to listen to the echo that is reflected. As previously mentioned the bat can release 200 pulses a second, so the pinna is moving in and out extremely quickly to pick up the reflecting echoes. The processing power of a bats brain means it can quickly perform calculations within milliseconds to help locate its prey. For example, if we assumed that the frequencies are travelling at 340 metres/second and the prey is stationary and the time it takes for the echo to bounce back into the bats ears is 0.3 milliseconds; then the distance of the prey is 0.102 metres. This simple calculation was performed by multiplying the speed of sound by the time it takes for an echo to reflect into the bats ears. This process is constantly occurring when a bat is hunting for food, which makes them a fascinating creature to study! This is a very simple mathematical calculation, however it is not as simple as this, as shown in the image below.
There are so many parts to the equation, which seem really horrible, but if the values are known, the equation is fairly straightforward, where all the products are multiplied together.
Learning how bats use echolocation to help source their prey and move around objects within their surrounding areas is useful for the future human, as it gives hope that one day we may be able to utilise this technique. It will require a lot of brain processing power, so as a result the human brain and skull would have to expand. I would assume that those with mental disabilities may not be able to utilise this technique, but for those who are blind, an adaptation of the bats echolocation is possible. As the human can’t produce high frequency sounds, a low frequency may work just as well. This is something that is already being used by some blind people, to help navigate their way around, even on bikes!
Jonathan.
National Parks, (n.d). Bats Echolocation. [online] National Parks: National Parks. Available from: http://www.eparks.org/wildlife_protection/wildlife_facts/bats/echolocation.asp [Accessed 8 March 2014].
Echolocation Diagram – Ask a biologist., (n.d). Echolocation in action. [online image] Available from: http://askabiologist.asu.edu/sites/default/files/echolocation.jpg [Accessed 8 March 2014].
SONAR Equation – Ulanovsky, N., (2011). Echolocation in bats. [online image] Available from: http://gorengordon.com/Teaching/ActiveSensing/Ehud_Ahissar_ACTIVE_SENSING_COURSE__Ulanovsky__Bat_Echolocation__1may2011.pdf [Accessed 3 April 2014].
University of Hawaii, (n.d). Bats Echolocation information. [online] University of Hawaii: Hawaii. Available from: http://www2.hawaii.edu/~zinner/101/students/YvetteEcholocation/echolocation.html [Accessed 8 March 2014].
Learning how bats use echolocation to help source their prey and move around objects within their surrounding areas is useful for the future human, as it gives hope that one day we may be able to utilise this technique. It will require a lot of brain processing power, so as a result the human brain and skull would have to expand. I would assume that those with mental disabilities may not be able to utilise this technique, but for those who are blind, an adaptation of the bats echolocation is possible. As the human can’t produce high frequency sounds, a low frequency may work just as well. This is something that is already being used by some blind people, to help navigate their way around, even on bikes!
Jonathan.
National Parks, (n.d). Bats Echolocation. [online] National Parks: National Parks. Available from: http://www.eparks.org/wildlife_protection/wildlife_facts/bats/echolocation.asp [Accessed 8 March 2014].
Echolocation Diagram – Ask a biologist., (n.d). Echolocation in action. [online image] Available from: http://askabiologist.asu.edu/sites/default/files/echolocation.jpg [Accessed 8 March 2014].
SONAR Equation – Ulanovsky, N., (2011). Echolocation in bats. [online image] Available from: http://gorengordon.com/Teaching/ActiveSensing/Ehud_Ahissar_ACTIVE_SENSING_COURSE__Ulanovsky__Bat_Echolocation__1may2011.pdf [Accessed 3 April 2014].
University of Hawaii, (n.d). Bats Echolocation information. [online] University of Hawaii: Hawaii. Available from: http://www2.hawaii.edu/~zinner/101/students/YvetteEcholocation/echolocation.html [Accessed 8 March 2014].