The vast ocean is home to millions of species that are yet to be discovered, each with several adaptations that are imperative to survival in the big blue. Eight minutes into the fourth episode of season 1 of Blue Planet II, David Attenborough and his colleagues set out to determine what traits the sperm whale has developed in order to increase its chances of survival. What they found was that sperm whales have the remarkable ability to use clicks to perform a variety of tasks, including communicating with each other. These clicks are amongst the loudest sounds produced by any biological source and are capable of piercing the big blue ocean with pulses reaching up to 130 kHz [1].
This ability is something that you see across several marine animals in the odontocete suborder. Historically, mammals in this suborder have experienced extreme predation from organisms such as sharks and other swift predators of the sea. It is theorized that these high frequency clicks evolved in these organisms to avoid detection by their predators who cannot pick up on sounds of this caliber [3]. Beyond that, these clicks can also serve as a type of sonar system for these mammals. This is important for deep diving hunts, because vision alone is inadequate to ensure food acquisition at the depths that they are capable of diving, which can be up to 1,000 meters [4]. These clicks are produced for the majority of the dive and increase in frequency when a sperm whale is moving closer to a prey, signaling to themselves and others that they are moving in the right direction. This is an example of what is known as a creak click, one of the three types of clicks that these mammals have evolved to use. The other two, usual and slow clicks, are more suitable for longer ranged echolocation and communication, respectively [2].
The sperm whale is truly an amazing and a magnificent animal. They are capable of producing extremely loud clicks that are capable of paralyzing their prey! However, sperm whales are relatively placid mammals and mainly utilize their clicks to communicate and find food, an ability that has allowed them to adapt successfully in the largest ecosystem on Earth.
by Jovanny Aguilar, Akash Patel and David Shon
Blue Planet II, Season 1, Episode 4, starting at 8:12
References
- Madsen PT, Carder DA, Bedholm K & Ridgway SH. 2005. Porpoise clicks from a sperm whale nose-convergent evolution of 130 KHz pulses in Toothed Whale Sonars? International Journal of Animal Sound and its Recording 15: 195-206.
- Madsen PT, Wahlberg M & Møhl B. 2002. Male sperm whale (Physeter macrocephalus) acoustics in a high-latitude habitat: implications for echolocation and communication. Behavioral Ecology and Sociobiology 53: 31-41.
- Morisaka T & Connor RC. 2007. Predation by killer whales (Orcinus orca) and the evolution of whistle loss and narrow-band high frequency clicks in odontocetes. Journal of Evolutionary Biology 20: 1439-1458.
- Watwood SL, Miller PJO, Johnson M, Madsen PT & Tyack PL. 2006. Deep-diving foraging behavior of sperm whales (Physeter Macrocephalus). Journal of Animal Ecology 75: 814-825.
The Evolution of Planet Earth 