Sperm whales are the most iconic cetacean species of the Azores.
They spend most of their lives underwater and dive on average around 40 minutes, but studies say they can dive more than 1.5 hours to depths up to 3,000 meters (Whitehead, 2003). Whilst underwater, they developed ways to communicate and orient themselves, especially at depths below the photic zone where dark prevails. They use echolocation, a system used by odontocetes (whales with teeth), which consist on a series of clicks produced by the animal to find their prey and to communicate amongst each other.
Since sperm whales are the largest odontocetes alive, with males reaching up to 18 meters in length and females up to 12 meters, they have a very large fatty organ in their head called spermaceti (see figure 1). This organ in the sperm whale takes up to 1/3 of the body length. Sperm whales can make many different types of echolocation consisting of clicks, slow clicks, creaks, trumpets, codas, etc.
But why do they use so many types of clicks?
Scientists use hydrophones to record those sounds and analyze them. Some of the different types of clicks are explained below.
Figure 1: how a sperm whale produces and receives sound (from the American Museum of Natural History, 2013)
Clicks & Creaks
Figure 2A. Usual clicks. B. Creak. Time in seconds in the horizontal axis (from Whitehead, 2003).
Figure 3: Coda. Time in seconds in the horizontal axis (Whitehead, 2003).
Figure 4: Slow click. Time in seconds in the horizontal axis (Whitehead, 2003).
So… why do they use so many types of clicks?
The above examples are only a few echolocation types of sperm whales identified by scientists. Over the years, scientists concluded that sperm whales are much more complex social animals than initially thought. Some of the most renowned sperm whale researchers in the world (e.g. Hal Whitehead or Shane Gero) explained that it is very important to study the sounds produced by sperm whales across the globe in order to understand how they group with each other and create a culture over the years they live together. If we don’t study their culture, we won’t understand their lives. So.. let’s study them!
Article by Fadia Al Abbar
– Federal Agency Review of Selected Airport Noise Analysis Issues, Federal Interagency Committee on Noise (1992). Source of the information is attributed to Outdoor Noise and the Metropolitan Environment, M.C. Branch et al., Department of City Planning, City of Los Angeles, 1970. http://www.gsweventcenter.com/GSW_RTC_References/1992_0801_FICON.pdf – Hoogenboom, M., (2016). The whales that speak in code. BBC. http://www.bbc.com/earth/story/20160120-the-whales-that-speak-in-code – Mohl, B. (2001). Sound transmission in the nose of the Sperm whale. Physeter catodon: a post mortem study. J. Comp. Physiol – Whitehead, H. (2003). Sperm Whales. Social Evolution in the Ocean. University of Chicago press.
Other links used
– Wikimedia. Sperm whale slow clicks. https://upload.wikimedia.org/wikipedia/commons/e/e9/Sperm_Whale_Slow_Clicks.ogg – Ocean Conservation Research. Creak of the sperm whale. https://ocr.org/sounds/sperm-whale/ – American Museum of Natural History. (2003). Whale biology. http://www.juansanmartin.net/undecima.html – BBC. Sperm whale call. 5r exchange at the onset of a dive. https://soundcloud.com/bbc_com/sperm-whale-call-5r-exchange-at-the-onset-of-a-dive