We hear animals communicate vocally throughout our day to day lives; birds singing, crickets chirping, and frogs croaking are only a few examples. Yet not a lot of people take the time to wonder, how and why are these sounds traveling and evoking a response from the receiver? Bats for example, produce calls that travel through the air in a unique way. They use echolocation to locate objects and search for prey. What’s even more fascinating is that bats actually construct unique signals by changing the frequencies, intensities, and harmonics. They also have different patterns in signaling, as the duration and intervals between calls also vary.
Even the environment around echolocating bats can influence their calls, as it can obstruct as well as aid these mammals in their endeavors. Echoes of certain leaves can serve as a disturbance to the bats search for food, but the echoes of other leaves can do the opposite. Other leaves in specific plants act as a sort of radar for the bats, as the echoes produced lead them to flowers that contain both pollen and nectar. It has been discovered that these ultrasonic guides are not always located on the flower itself, but often on the dish-shaped leave above it. This is true in the vine Marcgravia evenia, as the leaves above its flowers serve as a beacon for bats echoes and lead them to the nectar.
Although this echoing method of communication can be very helpful, it can also disclose information much more easily to potential predators or prey. To help diminish the risk of exposing information to possible prey, the bats manipulate the intensity of their calls by altering the frequency. For example the species Barbastella barbastellus can produce echolocating calls that are undetectable to moths while Eptesicus fuscus use harmonics to lessen interference.
Yet bat communication is not restricted only to vocal signals; it also extends to the olfactory system as well. In the species Saccopteryx bilineata, males use odors that are produced by composites stored in their wing sacs for mating. Vampire bats, belonging to the species Desmodus rotundus, are equipped with infrared detectors on their noseleaf, the same structures that are found in various snakes. These structures detect the heat from the blood just below the skin, and use this to locate their prey.
There are still so many unanswered questions about echolocation in bats like how it evolved and the functional roles of physical structure and ear movement. What we do know that this adaption benefited bats inside the realm of communication, as their signals can travel much longer distances as well as allow them to locate objects and prey. Through further research, we can gain more insight into the daily lives of these flying mammals and be able to really view the world through a bats ear.
http://www.sciencemag.org/content/333/6042/528.full?sid=763c97e8-6771-49c6-a2ad-9064db86ae55
Posted by Sara Corey(1)
So this isn't really about bats, but it is about bat's favorite food, the moth. So when bats are hunting moths, they trigger evasive behavior in moths and they do this cool thing called a power dive.
ReplyDeleteHow this works is when the bat is above the moth, the moth's receptors on their abdomen (its where their ears are located) are triggered which causes them to just fall straight down. I thought this was pretty neat and the behavior of bats triggers behavior of moths.
Posted by Whitney Huynh
This comment has been removed by the author.
ReplyDeleteMy first thought when reading this was "Hmm... I wonder how this applies to other echolocation using animals?" The way that a bat's environment can effect its calls is a fascinating concept, but imagine how it must apply to creatures such as whales and dolphins. If the vibrations in leaves can alter a bat's call, how do changes in the minutia of the ocean effect a whale's?
ReplyDeletePosted by Jacob Lane
Bats may have developed these awesome maneuvers to detect pray and flowers, but their pray has developed evasive maneuvers as well. As Whitney mentioned, one of the bats favorite foods is the moth. The moth has ears on its thorax to detect the radar signals of the bat. It uses the timing of these signals to figure out the direction of the bat and change direction to evade being caught by the bat's sonar.
ReplyDeletePosted by Noelle Kellicker
Cool post! Bats have a great range of signals and the vocal/auditory signals are probably their most versatile. Not only do they use their ability to emit high-frequency sounds for maneuvering through the air without vision, they can use these sounds to communicate with each other. Their frequencies may be out of reach of the audible range of other species, which is a smart adaptation. These flying mammals are truly one of the most unique animals.
ReplyDeletePosted by Michael Shi
This is a really interesting post. It discusses ways that bats can remain undetected by their prey, but it does not address how a bat does not give its location away to predators. I'm not even sure what predators a bat has, but if another animal could pick up on these signals as well it would be bad news for the bats.
ReplyDeletePosted by Michael Thomas
Last year I did an independent study that focused on the Doppler Effect and it's applications. One of the subtopics of my research paper was the biosonar that you discussed in this article. Not only do bats use echolocation, but certain species of birds do as well. The place where the Doppler Effect comes into play is how the animal makes adjustments in its calculations of distance. When a bat is flying and using it's biosonar, any clicks or shrieks they make will be distorted by the Doppler effect. Bats have an inborn ability to sense this frequency shift and use it along with their velocity of flight to calculate the distance of an object. They can also use echolocation to determine the velocity of prey as well, which is pretty cool when you think about it.
ReplyDeletePosted by Janelle Hayes
I know that not all moths have ear-like appendages, but it is really interesting to know that bats have become more adept at hiding their noises from the ones that do. I feel like this is a perfect example of the evolutionary arms race life-dinner principle, except in this case the bats seem to have the upper hand. I wonder how moths are going to combat the changing frequencies of the bats' calls.
ReplyDeletePosted by Rachael Mroz
I never realized bats had such control over their echolocation. I always figured it works like sonar in movies where there's just one chirp and they knew the shape of their surroundings. That certain leaf shapes could interfere never occurred to me. It's also impressive that they can modify the chirp so that the prey will not be able to hear it, this seems like an awesome hunting adaptation.
ReplyDeleteI was also surprised by the fact that bats communicate with each other through olfactory means. With such a specialized vocal system it seems like they would communicate mostly vocally.
Posted by Rhys Ursuliak
I was unaware that bats can adapt ways to change the frequencies of their sonar to be undetectable to certain prey such as moths. Moths actually have very intricate neural systems that help them to escape the predation of bats using the sounds made by them. This makes me wonder if the moths are evolving to form other ways of detecting their predators.
ReplyDeletePosted by Abbie Saranteas
This is a great example of co-evolution. As the bat got a huge advantage of finding moths to prey on , the moth's developed a way to avoid being eaten . At the same time the bat is now able to change the frequency of the noise to something the moth isn't familiar with. I'm sure there might be something like this with whales and other echo-locating mammals and their preys.
ReplyDeletePosted By Jobin Oommen
Echolocation, as far as I know, is mammal specific. I am curious to know how it appeared in the evolutionary tree. Was there a common ancestor, or were there multiple mutation points that led to this? If the latter, why haven't other animals developed it?
ReplyDelete-Joey Needleman
Like some of the other people commenting I had no idea bats could control their echolocation. Its really cool that bats can control the frequency of their calls in order to be more effective hunters. When I was younger I used to throw objects in the air at night and watch the bats swoop down to investigate. If you are interested in bats you should talk to Betsey Dumont who teaches mammalogy at UMass. She researches the different bites that bats can have depending on their prey, its pretty cool.
ReplyDeleteprevious post by Suzanne Sullivan
ReplyDelete