Annemarie Surlykke from the University of Southern Denmark is fascinated by echolocation. She really wants to know how it works.
Surlykke equates the ultrasound cries that bats use for echolocation with the beam of light from a torch: you won't see much with the light from a small bulb but you could see several hundred metres with a powerful beam. Surlykke explains that it's the same with echolocating bats.
Some have big powerful calls for perception over a long range, while others are said to whisper; which puzzled Surlykke. How could 'whispering' bats echolocate with puny 70decibel cries that barely carry at all? Teaming up with her long time collaborator Elizabeth Kalko from the Smithsonian Tropical Research Institute and student Signe Brinkløv, Surlykke decided to measure the volume of a pair of whispering bat species' calls to find out how loud the whisperers are. They publish their discovery that whispering bats are really shrieking in The Journal of Experimental Biology on 12th December 2008 at http://jeb.biologists.org.
Travelling to the Smithsonian Research Institute's Barro Colorado Island in Panama, Surlykke decided to focus on two whispering members of the Phyllostomidae family: Artibeus jamaicensis and Macrophyllum macrophyllum. According to Surlykke, the Phyllostomidae family of bats are unique because of their remarkably diverse lifestyles and diets. Some feed on fast moving insects while others feast on fruit buried in trees, making them an ideal family to study to find out how echolocation works.
But measuring the volume of the bat's echolocation calls was extremely challenging. If Surlykke was going to get true volume measurements from hunting bats on the wing, she would have to be certain that the bats were facing head on and that she could measure their distance from the microphone that recorded the sound so that she could correct for the volume lost as the call travelled to the microphone. Setting up an array of four microphones, the team recorded 460 cries, which Surlykke eventually whittled down to 31 calls for M. macrophyllum and 19 for A. jamaicensis that she could use.
Correcting the volume measurements, Surlykke was delighted to find that far from whispering, the bats were shrieking. The tiny insectivore M. macrophyllum registered a top volume of 105decibel, while fruit feeding A. jamaicensis broke the record at 110decibel, a remarkable 100 times louder than a 70decibel bat whisper and almost twice as loud as A. jamaicensis.
Surlykke suspects that she can explain the differences in the animals' volumes by their different lifestyles. She explains that the relatively large A. jamaicensis feeds on fruit, which it probably locates through a combination of senses, including smell and short-range echolocation whispers. But the bats have to search over large areas to find fruiting trees, and Surlykke suspects that the bat uses its high volume, well-carrying shrieks for orientation in their complex forest environment.
However, tiny M. macrophyllum's lifestyle is completely different. They hunt for insects over water, scooping them up with their tail. Surlykke says that she suspected that M. macrophyllum would be louder because she couldn't see how the animals could locate moving insects with a low intensity echolocation call, but admits that she was amazed that they were so much louder and that they could also adjust the volume to match their prey.
Kathryn Phillips | EurekAlert!
Bare bones: Making bones transparent
27.04.2017 | California Institute of Technology
Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
27.04.2017 | Life Sciences
27.04.2017 | Physics and Astronomy
27.04.2017 | Earth Sciences