Can You Hear it?
We highlight a wonderful art exhibit about the sounds of the animal kingdom in this week's blog. It features a great interactive online platform to listen to the sounds of the animal kingdom, in case you cannot travel to The Peabody Essex Museum to see it in person. the link can be accessed by clicking HERE. Image of the creator Bernie Krause recording nature below.
On this topic we focus on sound, and hearing. It is important to include both sound and hearing as these are separate. Hearing or auditory perception, is the act of an organism receiving sound stimuli, correlating and then converting that stimuli to something the organism can perceive. This seems to overcomplicate things, but it is important to distinguish between sound and hearing, as for every species of organism, sound is perceived differently. For example, rattlesnakes have no ears, and cannot hear like we do. Yet their jaw feels vibrations through the ground and they can perceive sound that way.
For example, your footstep makes a noise audible to us as you thud on the ground. This same energy that is released from your footstep and perceived by your ears, is also transmitted into the ground. The rattlesnake feels this energy in the form of vibrations through the ground and in that sense, hears your footsteps. Keep this in mind and have heavy footsteps near areas you may think a snake could be lurking. Also the rattlesnake's main predator deterrent is rattling. This is a behavior that creates a loud noise, meant to warn potential predators that the rattlesnake is aware and ready to strike.
It is fascinating that the rattlesnake, who wouldn't be able to perceive its own warning signal would still use it, and have it effectively deter predators. Sounds come in all forms. In fact certain spiders utilize a form of hearing known as near space hearing in which the noises made are not actually what is received, rather a change in pressure made by the sound waves alerts the receiving spider. Other spiders communicate using noise that we can perceive as well. They use their leg hairs to perceive the squeaking sounds made to lure in mates.
Some animals use sounds in a completely different manner; dolphins and bats utilize echolocation, and can hunt their prey almost entirely reliant on this sense. They emit a high frequency sound and have specialized sensors that pick up the same sound when it bounces back. This works by emitting the sound into the open ocean, in a dolphin's case, or the open sky for a bat. The sound travels out, and if there is nothing in the ocean or sky, the sound will not return to the one who made it.
However, if there is a prey item, a fish for the dolphin or an insect for the bat, the sound will return. It will bounce off the prey item and get sent straight back to the dolphin or bat. The speed at which the sound returns indicates how far away the prey is, and the angle at which it returns indicates where the prey is, and this way these hunters can locate food just by screaming at it!
Other animals use sound as well, even if they are not adept at making it themselves. The collared iguanid lizard of Madagascar uses a very interesting tactic to avoid predation. The lizard cannot make much noise, apart from a squeak when threatened. However, it has good hearing and will listen for the alarm calls of the paradise fly catcher. The flycatcher will make a specific alarm call when hawks or other large animals are in the vicinity, and the collared iguanid listens closely and takes cover when he hears the alarm.
Animals of all sorts make noise, and use sound in unexpected ways. Sometimes it can be beautiful, and create an orchestra of sound. If you haven't already, check out the art exhibit linked in the top of the post. Let us know about any other interesting ways animals use sound, or if any of this surprised you!
Photos taken by Isaac Yelchin and Alex Havasi. First image is from the exhibits website and is of the projects creator: Bernie Krause.
Isaac Yelchin is foremost a herpetologist. He studies lizards, frogs, newts, and the like. Specifically, he spends all day and night thinking about what it is like to be an animal. What are the animals thinking about? What is their perspective? When he should be working, he sits and stares at his pet lizard asking himself these questions.