Sonar – Part 1

This month, we start a new series on sound navigation and biology. The word sonar is an acronym for SOund Navigation And Ranging. Active sonar, emitting sounds and analyzing the returning echo, is primarily employed by people to navigate, measure distances, and detect objects in the water. The first recorded human sonar use was in 1490, when Leonardo da Vinci inserted a tube into the water in order to listen and detect approaching vessels. This was passive sonar. But certain animals have been using both active and passive sonar long before people navigated the oceans. The sophistication of these biological systems presents a profound challenge to evolutionary mechanisms. Consider owls. Like the da Vinci mechanism, numerous owls use passive sonar (or acoustic location). The “satellite dish” face of the barn owl (upper right) concentrates the sound waves. Their large ears are just beside the eyes. Unlike human ears, they are not symmetrical in height. This better allows them to pinpoint sounds vertically. By moving their head, they can “tune in” the sound of a mouse rustling far beneath them. Their faces “lock on” as they begin to silently glide head-first towards the prey. At the last instant, they twist about so that their talons are where their face was. The owls are so precise that they consistently strike the rodent broadside. Experiments taking place in the complete darkness of a windowless warehouse confirm that owls can use only their ears to pinpoint the prey. An owl flying 150 feet in the air at a speed of 50 mph can hear a vole rustling a foot beneath the snow and precisely dive upon it! Owls enjoy a specialized set of auditory pathways in the brain to accomplish these astounding feats. Soft, serrated feathers dampen the sound of the owl’s flapping wings so as to not disturb the prey or their own acoustical analysis. The Bible mentions multiple kinds of owls in Leviticus 11…the little owl, the short-eared owl, the barn owl, and the tawny owl. These amazing nocturnal creatures are so specialized and irreducibly complex that it is difficult to think of them morphing slowly over millions of years by accidental mutations. No, they are instead marvels of divine engineering!

Posted on November 1, 2022 by dwoetzel.