Featured Image Credit: Youtube
By Eva Gruber
Marine biologists have discovered a previously unknown feature of whale song.
Whales communicate underwater in order to find each other, and possibly to share information in much the same way that humans share information about their environment. Now, with new technology, we are starting to piece together the secret components of this majestic animal’s haunting tunes.
Published in the online journal Biology Letters, the results were the findings of the Woods’ Hole Oceanographic Institution (WHOI). Dr. Aran Mooney from WHOI traveled to the island of Maui in Hawaii to track a group of humpback whales during their migration. The scientific team dropped equipment over the side of their boat to measure the movement of particles and water pressure during the whales’ calls.
Their guess was that there wouldn’t be much particle motion – at most, they’d be able to detect moving particles from several meters away. The results of the experiment shocked them all – they were able to pick up particle motion from 200 meters away, and the recordings suggest that they could travel much further.
The researchers’ goal was to study the different ways in which whales communicate with sound. Their scientific gear was equipped to measure two components of sound waves. Pressure waves, measured by a hydrophone, result from the compression of molecules as sound moves through the water. This is how we hear sounds underwater – the pressure waves vibrate our eardrums, which we perceive as sound.
The second component, an underwater accelerometer (which is a pretty modern and high-tech piece of equipment) measured the vibration of the water molecules, caused by the physical vibration of the sound waves. This effect can be compared to the vibration you feel when a nearby car is blasting hip-hop music’s deep bass lines.
While whale song has been studied for a few decades now, not much attention has been paid to the motion of particles – the vibrations caused by whale song. The particle motion tends to be more difficult to study than pressure waves – there is not a lot of understanding about how it propagates through water as opposed to air, which is much less dense than water.
We do not yet know if whales can detect the vibration of particles with their senses, but unlink any other mammals, humpback whales’ earbones are fused to their skulls which provides a direct link to the brain – meaning perhaps they are more sensitive in picking up vibrations in the water. It is suspected that perhaps the humpbacks use their lower jaws as a kind of tuning fork.
Many other animals have been shown to use vibrations to communicate, such as elephants and hippos – so the possibility is there. These findings could be cause for more concern about the role of anthropogenic sound in the ocean – noises from seismic blasts, cargo and cruise ships, and submarines may cause much more harm than previously suspected.