Barely a day goes by that my mind isn’t blown by some new thing I’ve learnt about wildlife. Either something I’ve seen or something I’ve read, or something I’ve been told about the natural world.
I’ve recently learned that White-fronted bee-eaters have family clans that fight off other clans from feeding grounds. I’ve found out that there was a penguin species (now extinct) that stood over two metres tall, and one of my new favourites is the fact that praying mantises – themselves fairly vicious creatures in that the female bites the male’s head off during mating – manoeuvre like fighter planes to avoid being eaten by bats, reacting to the bats’ echolocation and diving out the way at the last minute.
For most tricks in nature, there is another trick to overcome it, and in this case, the mantises make use of a single ear found in the centre of their chest to calculate the exact moment before a bat is about to strike, and react accordingly.
Insectivorous bats hunt on the wing through echolocation; they emit a high frequency sound and are able to calculate from the echoes that bounce back to them what is ahead; they can work out how an insect is flying, its speed its direction… all the information needed to successfully pluck it out of the air.
As they approach their intended target, the frequency of their vocal emissions goes up dramatically so that they are getting almost constant information on the target. On still nights at Londolozi, you can sometimes even hear the bats hunting above you, their trilling rising to an almost imperceptible whine as another insect meets its demise. For the most part though, their echolocation takes place outside the range of human hearing.
Much like a submarine that will know when it is being actively pinged by sonar underwater, praying mantises when flying are able to tell when they are being echolocated by a bat.
I don’t know about the specific neurology of a praying mantis, but I imagine the information from this echolocation detection has to be lightning fast in order for the mantis to react in time. They judge to the millisecond when they are about to be gobbled, and in that instant they drop into a vertical dive to evade the bat’s searching jaws. Too early and the bat will have time to adjust its approach. Too late, and…
Apparently the mantises have become so good at judging when to power dive that they get away about 80% of the time!
It’s very unlikely any of us will get to see these mantid evasive manoeuvres. Spotting a flying mantis at night is hard enough, then to keep one in the spotlight long enough for a bat to come along is invariably going to be tricky. I just feel that facts like this should be shared so that more people are able to marvel at how wonderful nature is. Incredible little dramas and survival stories are happening all around us, all the time, the vast majority of which go unseen and therefore unappreciated.
But if I happen to see a mantis land one evening in the near future, then see it take off into the darkness, I’ll give it a nod and genuinely wish it luck. But with an 80% success rate, it’s probably not going to need it…