WHALES - COMMUNICATION AND SONG2014
By Amelia Meyer
Whales have advanced methods of communication, ones that have intrigued researchers for as long as they have been studying these animals. Communication amongst animals is essential to mating, training offspring, finding their way and warning of dangers.
A major component of the interpersonal communication of whales is the use of songs. Humpback Whales are particularly well known for their songs, which are sometimes quite complex in their structure. Sound is an effective means of communication for marine animals, since sound waves travel about four times faster in water than in air, and are optimally amplified by the denser medium.
The sounds created by whales are structured in a similar way to human musical compositions and are, therefore, called songs. However, clicks and clicking sequences are also used. In fact, the different sequences and ‘compositions’ are so unique that individual rhythms may, in fact, identify specific whales. They are also used to coordinate foraging activities amongst the individuals in a pod.
Toothed whales and baleen whales use different methods to create sounds. Toothed whales (Odontoceti) use only high-frequency clicks and whistles, rather than songs. These are emitted in rapid bursts. Usually, a single click will be used for echolocation purposes, while the longer combination of clicks and whistles is favoured for communication. These sounds are produced by passing air through the phonic lips, which are a structure contained in the head. Air passes through the narrow passage and the lip membranes are sucked together. This causes the tissues around the lips to vibrate. The entire process, including the vibrations, is carefully controlled by the animal. These vibrations pass through the various head tissues into the melon, which then directs these sounds into a beam that can be directed from the front of the head (especially useful for echolocation). The air passes from the phonic lips to the vestibular sac and can then either be recycled for sound creation again or passed out through the blowhole. Toothed whales all have two sets of phonic lips (with the exception of the Sperm Whale) and can, therefore, emit two different sounds at once.
Baleen whales do not have the phonic lips, but a larynx and cranial sinuses. However, the exact mechanisms used are not well understood by researchers, as it is very different to both toothed whales as well as humans. What is known is that baleen whales produce sounds ranging from 10 Hz to 31 kHz. Humans are able to detect sounds ranging between 20Hz and 20kHz only.
In addition to songs, whales use grunts, groans, snorts and barks as part of their audible communication. The Beluga Whale is believed to produce the most varied combination of clicks, whistles and pulses when communicating.
Pods form their own dialects, which are unique to them. It has been shown that certain pods actually teach their young the same patterns of communication. Whales from certain geographical regions sing similar (although not identical) songs. Calves will develop a similar singing pattern to their mothers, who teach them. In addition, studies have indicated that some whales even revert back to a common chorus when singing certain songs. When certain patterns evolve into more advanced singing structures, the whales have been shown never to revert back to their old patterns. This is an incredible insight into the effectiveness of their communication.
The noises made by cargo ships and large passenger ships, as well as by fishermen that are using acoustic tools to find fish, are threatening the whales’ dependence on audible communication and, therefore, their very survival. It is believed that very loud sounds generated by humans have been behind the stranding and subsequent deaths of many whales. Some man-made noises cause haemorrhages near the animals’ ears and decompression disease as they attempt to leave the depths of the water too quickly, disoriented by the sonar.