One of the most interesting topics regarding cetaceans is how these animals communicate underwater. Moreover, it becomes even more challenging in environments where unfavorable conditions impair vision and smell. Therefore, let’s explore how whales and dolphins communicate in such conditions.
Scientists consider whales and dolphins to be among the smartest animals on Earth. They exhibit various cultural practices, teaching their young essential survival behaviors (Bender et al., 2009). Therefore, communication plays a key role in these animals’ social lives and, consequently, serves as one of the main proofs of their high intelligence.
How do Dolphins Communicate?
Dolphins communicate through the emission and reception of sounds. Each dolphin develops its distinctive sound within the first years of life. All individuals produce a unique sound, different from others’, so they can identify each other; it is like us humans with our names. On our trips, you can often hear their sounds!
But dolphins also use different behaviors or body language to communicate with each other. In almost all of our tours, we can observe some of this dolphin communication, like the following:
Postures
Body postures can sometimes demonstrate anger or aggression in dolphins. For example, the S-posture is typically used in two specific social contexts: courtship and aggression. Male dolphins fight with one another for many reasons, including over resources such as food and space, females, and status (Waal & Harcourt, 1992).
Touch
The skin of these cetaceans is very sensitive to the touch. If they are in a good mood, then they can make physical contact with the flippers by pressing them against the flippers of another dolphin (Azevedo, A. et al 2010).
Tail Slapping and Flipper Slapping
It is a vertical blow of the tail or flipper against the water surface that sometimes indicates aggressiveness, but it can also express a desire to leave the area or to attract the attention of other dolphins (Azevedo, A. et al. 2010; Herzing, 2000).
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Bow-riding
Perhaps this is the most common behavior that our tourists can see on our tours. Dolphins approach our bow and are propelled by the vessel’s waves. Dolphins have learned to harness this “free” energy and take advantage of the opportunity to rest. And at the same time, they are having a moment of fun.
Identification of body coloring patterns
Stains, stripes, and specks may indicate the health status or the age of dolphins’ companions.
For example, the skin of the Atlantic spotted dolphin (Stenella frontalis), which arrives at the Azores in the summertime, develops spots when it grows older, and the scars in the skin of the Risso dolphin, one of our resident species (Grampus griseus), inform others of its combat skills and experience.
How do Whales Communicate?
The deep is, despite its quiet appearance, the realm of sound, as it travels in water four times faster than in the air. As a consequence, cetaceans are extremely sensitive to sound, with three times as many neurons dedicated to sound perception as in humans.
They are also known to have the ability to hear up to 12 octaves, while in comparison, humans can only hear up to 8 (Ketten, 2018).
But because they operate at different parts of the spectrum, not all cetaceans can hear one another underwater. The types of sounds produced and perceived vary by species and can include clicks, pulses, whistles, groans, cries, or trills.
Communication Differences between Cetaceans
Baleen Whales (“Mysticetes”)
True whales, such as blue whales, humpback whales, or minke whales, belong to the group “mysticetes” or “baleen whales”. They get this name because, for feeding, they use hair-like structures called “baleen plates” in order to filter plankton and krill out of the seawater. To communicate, these whales produce low-frequency sounds with the help of their larynx (Figure 1).
Some of their vocalizations are very complex and consist of various units, organized into phrases that, in turn, form different themes. When several themes are arranged into a specific order, a song is formed. For instance, one of the best-known mysticete songs is that of the humpback whale, which is possibly the longest (7-30 minutes), loudest, and slowest song in nature (Payne & McVay, 1971).
Male humpback whales of all ages form aggregations to sing, which is thought to be a territorial display or a way of attracting females, and thus plays an essential role in sexual selection. Most of the singing is performed during the breeding season, but male humpbacks have also been known to sing while feeding.
Each population of humpback whales has its own unique song, with the same themes being repeated in the same order. However, these change over time, when different units or even different themes are added to them or exchanged. Therefore, over a few years, the same population will be singing a completely different song, which may increase the population’s reproductive fitness, as in the case of birds (Garland et al., 2011).
Here is an example of a humpback whale song.
Toothed Whales (“Odontocetes”)
Other cetaceans, such as sperm whales and all dolphin species, feed on larger prey, including fish, squid, and even other marine mammals. They have teeth instead of baleen plates and therefore belong to another group called “odontocetes” or “toothed whales”.
These animals use their larynx and nasal sacs to produce various types of sounds of mid to high frequency, not only for communication purposes but also for navigation and hunting.
All odontocetes are capable of biosonar, or echolocation, which helps them orient themselves in the dark and find prey. Above all, this feature is based on the production of a series of clicks directed through an organ called the “melon”, found in the forehead of the animal (Figure 2).
The clicks then bounce off various objects or creatures and return to the cetacean, which captures them through fatty tissue in its mandible, connected to the middle ear. The vibrations are later transmitted to the animal’s nervous system, which interprets them and translates the information into a mental map of the environment, allowing the animal to clearly see the positions of any obstacles and/or food sources.
Despite their essential role in navigation and hunting, clicks are not so much used for communication. For this purpose, dolphins use burst pulses and whistles, and it has been shown that each individual produces a characteristic sound, called a “signature whistle”, which acts almost like its name (Sayigh et al., 2007).
Although these whistles lack the complexity of mysticete songs, experiments in captivity have shown that dolphins have a high understanding of both syntax and semantics and can associate different sounds with different objects and even mimic human behavior and sounds.
What do Whales Sound Like
Beluga Whale Sound
Bowhead Whale Sound
Gray Whale Sound
Humpback Whale Sound
Minke Whale Sound
Right Whale Sound
Sperm Whale Sound
CHAT Box – “Cetacean Hearing and Telemetry” Project
Based on this research, scientists from The Wild Dolphin Project and Georgia Tech joined forces in 2010. Together, they worked with wild Atlantic spotted dolphins in the Bahamas. As a result, they developed the “CHAT box”, a computer that stores artificial whistles linked to specific objects.
The use of this machine demonstrates that dolphins can learn new “words” and associate them with objects that are not naturally part of their environment, and it is a first step toward a better understanding of cetacean communication.
You can learn more about this project on its website: CHAT Research and listen to common dolphin sounds.
Threats to Cetaceans’ Communication
Given that sounds play an essential role in vital behaviors such as foraging, spatial orientation, social interactions, and breeding, cetaceans are very sensitive to loud noises.
Various forms of human activity at sea, such as boating, seismic surveys, and military exercises, produce noise levels that interfere with communication and can harm whales and dolphins, altering both their behavior and physiology.
Humpback whales, for example, have been observed to avoid certain feeding grounds in the presence of noise sources (Risch et al., 2012), while deep divers such as different species of beaked whales have been found to mass strand when associated with military exercises (Fernandez, 2004; Frantzis, 2004). It is therefore essential to continue learning about how these animals use sounds and how noise affects them in their environment, in order to design and implement the best management procedures for their protection.
Written by Ramona Negulescu
References
- Bender, C. E., Herzing, D. L., & Bjorklund, D. F. (2009).
- Fernandez, A. (2004).
- Frantzis, A. (2004).
- Garland, E. C., Goldizen, A. W., Rekdahl, M. L., Constantine, R., Garrigue, C., Hauser, N. D., Michael Poole, M., Robbins, J., & Noad, M. J. (2011).
- Ketten, D., The University of Rhode Island (Producer) (2018).
- Dr. Joy Reidenberg. Adapted from Joy S. Reidenberg and Jeffrey T. Laitman. 2007.
- Risch, D., Corkeron, P. J., Ellison, W. T., & Van Parijs, S. M. (2012).
- Sayigh, L. S., Carter Esch, H., Wells, R. S., & Janik, V. M. (2007).
- The Wild Dolphin Project (2010).
