When we think of whale song, we think of long mournful yet musical cries echoing through the ocean. We may listen to the song of the humpback to relax, in the bath or when reading a book, and some may even use it during labour. I always used to listen to it when trying to revise for important exams as I found that it had quite a calming effect on me, and subsequently I found it much easier to remember information. I’m sure many of us are well acquainted with the soothing sounds and have surely heard it at some point before. Perhaps we even listen to it quite often and so it may come as a bit of a surprise to learn that even to this day it remains something of a mystery. However, this may be about to change as a recent study has revealed an interesting and previously unknown element of the beautiful and haunting song.
In 2016, the Woods Hole Oceanographic Institute (WHO) published a new study regarding humpback whales and their songs. The study uncovered a new component of the songs previously overlooked in the past. This is thought to be incredibly important in furthering our understanding of whale communication and hearing.
Throughout the study, biologist Aran Mooney and the research team based themselves off the coast of Maui in Hawaii. They centred their studies upon the local humpback whale population and focused on two key elements of whale song: pressure waves and particle motion. Pressure waves are the waves that vibrate against the ear drum and allow us to detect noise. Imagine you are sat in your house and a neighbour starts playing loud music nearby. Obviously you can hear it and that comes as a result of the pressure waves. You can also feel a vibrating in your chest and on your chair, like a deep, rumbling vibration. That is known as particle motion and it is an aspect of whale song that, up until now, has been fairly lacking in research. Unlike pressure waves which can be monitored through the use of a hydrophone, a well-used and easily accessible piece of equipment, particle motion must be recorded via an accelerometer. This equipment is hard to come by and is not often available for researchers to use. Luckily, Mooney and the team had access to both.
What did they discover?
According to Mooney, it came as quite a surprise to discover that the particle motion of the humpbacks’ songs travelled considerably further than expected. After allowing themselves to drift away from the whales whilst continuing to monitor the sounds, they learned that it was travelling up to 200 metres with the potential to move even further. This is incredible in itself, and it is believed that particle motion could be a whole new strand of cetacean communication.
What does this mean for the whales?
Firstly, it means that scientists are closer to finding out more about the true use of whale song. Whilst the songs have been studied comprehensively in the past, the exact reason that humpback whales use them remains elusive. Generally, it is believed that they play an important part of their mating ritual, with the males using the longest and most complex songs to win the females. However, it is widely believed that they may also be used in feeding, socialising and competing. This discovery, it is hoped, will contribute to understanding more about whale communication as it adds a whole new aspect. If the anatomy of the whale is anything to go by, then there is the potential that they have the ability to sense the vibrations in much the same way as elephants do through their feet. With their ear bones attached to their skulls in a way that would allow them to pick up such vibrations, it could be that this previously overlooked component could prove to be a key part of both communication and hearing. The team have stressed that further studies are vital in understanding exactly how whales use particle motion, but it is a step forward in learning more about the mysterious and secretive world of whale song.
Continuing with the impact that the study will have upon the whales, it is important to address the concerns of human noise in the ocean environment. It is a well-known fact that we are having a truly detrimental effect on our oceans ranging from the use of plastic to abandoned fishing gear and shark nets, but it is the noisiness of human activity raising concerns here. If this vibration does prove to be vital in whale communication, then it might be assumed that we are having a more terrifying impact.
Particle motion, as mentioned, travels at a very low frequency as does the noise of shipping, seismic exploration and leisure activities. Does this then mean that we are effectively drowning out the whales whilst they try to speak to each other? If we are in a crowded room, full of people shouting and singing and generally making noise and then try to talk to somebody, it is very, very difficult to do so. It is frustrating and hard work. So imagine how much worse it would be if you didn’t know these people and they had just wandered into your home and started making a noise. It would be unbearable and incredibly infuriating. As Mooney says, noise in our oceans is often overlooked, we do not hear it and so cannot necessarily equate our actions with consequence. For the whales and other marine life, though, there is no doubt that it can be damaging. We already know that many fish depend upon particle motion and so can potentially be affected badly by noise hitting the seabed from seismic or pile driving activities.
Of course the WHO study is just one drop in the ocean of research and, I predict, it is the start of many similar studies to come. However, it does raise some very interesting questions and certainly sheds more light on the strange and secretive watery world of the whale. What can be said for certain is that the more we learn and continue to discover about our world, the more can be done to make a difference to help us to protect and conserve our environment.