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One of the few places I find my emotions occupying the small overlap between excitement and fear is the bat cave at the zoo. Knowing that bats use sophisticated echolocation to build a detailed picture in complete darkness helps settle my nerves a little. Yes, they can see where they are going, and they are not going to fly into me … unless they want to! It has been suggested that this amazing echolocation system allows a bat to build a mental image of its surroundings that is close to the detail of the visible image from eyes of daytime animals. The bat sends out ultrasonic clicks, which reflect off surrounding objects back to the bat’s ears. When scanning for insect prey, bats may send out around ten clicks per second, and then increase this to over 100 per second when they locate an in-flight meal.
God has, however, given humble insects a range of impressive strategies to give them a fighting chance, even at the low end of the food chain. Many can detect bat sonar and react with evasive flight techniques. For example, when the hawk moth picks up the slower, scanning clicks of the bat, it will fly in the opposite direction. If it detects the faster kill clicks, and is now in big trouble, it will fly in zigzags, loops, or power dive toward the ground.
The green lacewing folds its wings and freefalls in response to the slower clicks of a scanning bat. If it then picks up the rapid click rate of a bat attempting a kill, it quickly opens its wings to suddenly break the dive and confuse its predator One of my favourite tactics used by insects is signal jamming. The tiger moth produces its own ultrasonic clicks that mix with the signals from the bat and distort them.
Recently, it was discovered that some insects have specially designed scales on their body which absorb sound waves, making them almost ‘invisible’ to bats. Researchers at the University of Bristol found that some moth wings absorb around 87% of all sound energy, making them about ten times more effective than the best technologies humans have engineered. Look out for noise-absorbing wallpaper inspired by moths, because we are thinking of copying this wonderful design. This is one of many examples of products for which our Creator ought to get the credit.
‘The Ultrasonic War Between Bats and Moths’, https://www.icr.org/article/ultrasonic-war-between-bats-moths (Accessed 03/05/2023)
‘Moth wings as sound absorber metasurface’, https://royalsocietypublishing.org/doi/10.1098/rspa.2022.0046 (Accessed 03/05/2023)
