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Cetacean Communication: Who Talks and Who Listens Importance of Research on cetaceans: How they communicate Mimicry, Sound, and the Effect of Emotions on Vocalization Background: • Cetaceans are whale, dolphin, and porpoise marine mammals. • The three main cetacean that will be discussed will be the orca whale, bottle nosed dolphin, and the beluga whale, all of which are known as Odontoceti or toothed whale. • These toothed whales are highly sophisticated in vocalization, communication, and mimicry. It wasn’t until the 1940’s when research on underwater sound was taken seriously. Once the use of hydrophones came into affect, scientists were able to hear the sounds and speech of marine mammals like cetaceans. They are able to detect calls on frequencies unobservable by human ears. They have been able to research the anatomical parts of cetaceans used for communication. However, the one question that still remains today is, what are they communicating? Social aquatic animals usually will rely on auditory communication. This means that large social structures in cetaceans are imperative for auditory communication, verses other marine animals like sharks who live independently. Anatomy of sound: Cetaceans all produce sound through the part in the body called the larynx. Unlike primates, cetaceans lack vocal folds and instead have fat bodies and accessory air sacs in their nose. The toothed whales also are able to produce high frequency calls through their nasal passageways. The movement of air pushed through the phonic lips causes vibrations to occur and the air sacs will act as natural amplifier. The sound then travels through the fats inside the melon in the head, and is distributed in the water in front of the animal. The unique sounds produced are because of the precise channeling inside the melon. It is said that the sounds produced for communication and echolocation are produced simultaneously but are received through the lower jaw through an oil filled channel and is then passed through to the middle ear. When the sounds are released they are released in low frequencies . These echoes bounced off from objects in front of the animal’s give information about water depth and landscape all the way to what other animals are around them. It gives them a three dimensional view of the world. References: Bates, Mary. "Dolphin Hear, Dolphin Do: Imitation by Echolocation | WIRED." Wired.com. Conde Nast Digital, 3 Oct. 2013. Web. 26 Apr. 2015. "DOSITS: How Do Marine Mammals Produce Sounds?" DOSITS: How Do Marine Mammals Produce Sounds? University of Rhode Island, 2014. Web. 24 Apr. 2015. Kirby, David. "Captive Killer Whales Learn to Speak Dolphin." TakePart. N.p., 9 Oct. 2014. Web. 23 Apr. 2015. Mead, James G. "Sound Production and Communication." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 26 Apr. 2015. Siebert, Charles. "The Story of One Whale Who Tried to Bridge the Linguistic Divide Between Animals and Humans Read More: Http://www.smithsonianmag.com/science-nature/story-one-whale-who-tried-bridge-linguistic-divide-between-animals-humans- 180951437/#yvq14mZiYFy2oymj.99 Give the Gift of Smithsonian Magazine for Only $12! Http://bit.ly/1cGUiGv Follow Us: @SmithsonianMag on Twitter." Smithsonian. Smithsonian Magazine, June 2014. Web. "SMS-491." SMS-491. N.p., n.d. Web. 26 Apr. 2015. "Whale Communication: Who Talks & Who Listens." Whale Communication: Page 3. N.p., n.d. Web. 26 Apr. 2015. Conclusion: • Cetaceans are intelligent marine mammals that communicate through sound and visual gestures. They produce sound through fat bodies and accessory air sacs in their nose. • Toothed whales are able to produce high frequency unique whistles and calls through nasal passageways. They are able to change their frequencies to mimic and perform interspecies communication. • Dolphins were among the first cetaceans to be researched for their oral communication. • Orcas are know n for mimicking dolphin calls when placed in an environment with them. • beluga whales became famous for being the whale with one of the highest range of vocal frequency, and when Noc made headlines for mimicking human speech to try and communicate. Mimicry Research and testing: Three main research project: 1. Dolphin Hear, Dolphin Do at the Dolphin Research Center 2. Orca mimicry of dolphins 3. Noc, the beluga who speaks human Vocalization/sounds/communication: Toothed whales are known to produce loud burst/ pulsed sounds along with visual communicative bubbles , tail slaps, and jaw claps. In the first wavelength picture and spectrogram it shows four jaw claps compared with four burst pulsed of sounds of an aggressive beluga whale. The wavelength shows the bursts of sound where the x axis is time and the y axis is the amount of energy released. The spectrogram measures time and energy released in kilohertz for the jaw claps. In all toothed whale pods, each individual has their own specific vocalization. They are able to keep in contact with individual using short range calls. Since pods are constantly changing in size and individual members, so each one having their own signature whistle is imperative. Whistles are a type of tonal sound that can change in frequency. Since each individual has a different whistle it is used to identify the whale/dolphin that produce it along with its location. In spectrograms, like the three above, the loops display the unique indivual dolphin whistle. The amount of loops can change for each whistle, but the shape of it will never for that individual animal. Two types of cetaceans, sperm whales and orcas, have unique pod communications. Each pods have there own specific calls and frequencies as well. These calls are for long term communication so that an indivual or small group can make there way back to the larger pod. In orcas, pods produce different clicks, whistles and pulsed calls. These calls are then separated again into wither discrete or variable calls. Discrete calls are the calls that are unique to each individual pod and are used for identifying pod groups and coordination of the group structure. Variable calls are used for coordinating social events among many pods. The spectrogram above shows individual calls of two separate pods. Each indivual of its specific pod have very close similarities, but when the two pods are compared to each other they are very different. These animals also produce acoustic communication by using non vocal sounds. Tail and fluke slapping against the water makes a loud noise that can be heard under the water. Some researchers say this can indicate wear a school of fish are, while others say it’s a sign of aggression. Another sign of aggressing is jaw clapping which makes a type of bang sound. 1) Researchers at the Dolphin research Center in Florida in 2010, showed how dolphins are ably to mimic behaviors without using their sight. They set up the first experiment by blindfolding a dolphin named tanner with soft latex eye cups. He was laced in the water with another dolphin in order to imitate his behavior. Next he was placed in the water with a human in order to mimic their behavior. It was shown that Tanner used only his hearing to understand the movements of the dolphin. However, because humans and dolphins make very different sounds when moving in the water, Tanner had to use echolocation to “see” what the human was doing. This flexible change in strategy has shown that he has used imitation or mimicry as an “intentional problem solving Process”. 2.) A new research study at the Hubbs- SeaWorld Research Institute has found that orcas living with captive bottle nose dolphins will change their speech pattern to create more vocal conformity and plasticity. Three killer whales kept in captivity with dolphins were compared with seven killer whales living in captivity with each other and no dolphins. The killer whales living with dolphin's changed their speech to use more clicks and terminal buzzes rather than the regular pulsed calls and squeaky burst sounds that the seven other orcas were making. The orcas not exposed to the dolphins never once made any terminal buzzes and very few clicks. 3) In the 1960’s The US started using dolphins and other whales for recovery of torpedoes and submarine detection, By the 70’s the soviets started hiding submarines in the arctic where most mammals could not get to except for beluga whales. In 1977-0, six belugas were caught to use for the navy including Noc who was the youngest. Once Noc was in semi retirement after catching meningitis, one of the divers heard a strange noise sounding like someone telling him to get out. Turns out it was actually Noc imitating human speech pattern. With further testing, the rhythm, amplitude, and intervals of his vocals matched up with human speech. His frequencies measure between 200 -300 hertz, which is not only that of a middle c, but also many octaves below that of a regular belugas sound. They were able to place a device called a ”rapid response pressure catheter” into his nasal passages and air sacs to monitor his vocals. They found he was able to change his sound by over inflating his nasal cavities to the point where it seemed his melon would almost burst, just to get his sound into the normal human tenor. Further Research: • Finding out if the use of vocals and sound for mimicry is fully intentional in the learning processes of cetacean life. • Do they only use mimicry for already known behaviors, or is it used when learning new behaviors in the same species or between species. • Is interspecies communication actually learned and understood for things like finding other pod locations for food sources or social contact. Figure 7. Intensity and range of detection of marine mammals (based on data from table 1). From Dusenbery (1994). Spectrogram dolphin 1 Spectrogram dolphin 2 Spectrogram dolphin 3 orca pod 1 wavelengths orca pod 2 wavelengths beluga aggression pulses vs jaw claps
