How do whales and dolphins talk?
A guide to marine mammal communication
Most of us are aware that marine mammals like whales and dolphins can ‘talk’ to each other through sounds like whistles, clicks, squeaks and ‘song’. Auckland Whale & Dolphin Safari marine scientist Kirsty Goode looks at the science behind marine mammal communication and explains some of the recent research that’s giving us insight into how and why they do it.
What is communication?
First of all, let’s start with the basics. Communication is the process by which a sender produces a signal. That signal may alter the probability of a response behaviour by the receiver. For humans, communication can come in the form of verbal words, nonverbal social cues, sights, smells, feels… the list goes on.
However, some forms of communication are easier, faster or more effective at getting across a specific idea. For most of us this would be a shared verbal language – that is, talking to each other! This general principle applies to marine species as well.
How and why marine life communicates
Different marine animals are adapted to using different senses for their primary forms of communication. They might communicate in order to find a mate or sense predators and prey. For example, sharks rely heavily on their sense of smell and are well adapted for it. In fact, up to two-thirds of the total weight of their brain is dedicated to smell. Because of this, they can detect the blood of prey from a huge distance, and at a concentration as low as one part per million – that’s about the equivalent of a teaspoon into an average private swimming pool!
Another contrasting example is the strategy of cephalopods (species like octopus, squid, and cuttlefish). These animals have evolved to communicate complex visual cues using cells on their skin called chromatophores. These remarkable cells can cause colour, texture, and size changes within a fraction of a second. They use this ability to evade predators, capture their prey, and to communicate between themselves.
Cetacean communication
This brings us to cetaceans, or our beloved whales and dolphins, such as those we encounter here in the Hauraki Gulf. While cetaceans do use smell, sight and touch as cues, their most effective mode of communication is through acoustic cues, or sound – both vocal and non-vocal. Sound travels very easily and effectively underwater – four to five times faster than above water – and its signal strength is not as greatly reduced over large distances compared to light (aka visual cues).
For this reason, sound has evolved to be one of the principal modes of information transmission for intelligent species like whales and dolphins, who have the capacity to learn complex combinations of sounds to mean specific messages (like languages in humans). We are lucky enough to witness many of these acoustic cues each time we go out on safari!
Non-vocal cues might include things like noise from flukes or flippers slapping the water’s surface causing a percussive sound underwater. When a cetacean jumps fully out of the water it’s called breaching, and this produces both an airborne and an underwater sound that carries for several kilometres and can signal other animals in the area.
Cetaceans also take advantage of the acoustic cues that other species produce. For example, during feeding aggregations (or work-ups) we frequently witness the large Australasian gannet plunge-diving into the water for fish. We know the tell-tale ‘thump, thump’ sound produced by the gannet diving into the water acts as a signal which draws common dolphins or even the resident Bryde’s whales into the area to feed as well.
When it comes to vocal cues, there are considerable differences between the vocalisation types and strategies of the baleen whales and the toothed whales. In general, baleen whales travel huge distances during annual seasonal migrations, either alone or in relatively small groups. This means their vocal communication needs to cover huge distances for the receiver to get the message.
To this end, baleen whales often produce intense, prolonged calls at very low frequencies which carry for tens to hundreds of kilometres. It is even thought that the blue whale produces a sound so powerful that it can carry for over 1500km across ocean basins!
Song of the humpbacks
One of the most well-studied species of this group is the humpback whale. Research on humpback populations and individuals has revealed the complex composition of their calls, with researchers able to discern a structure consisting of individual units (or words) which form phrases and themes in a repeating arrangement. There is a better-known word for this… language!
Scientists have not quite reached the point where they can ‘translate’ humpback whale song, but studies have been able to link specific units or phrases with specific behaviours, individuals, or interaction types. We have even learned that the song changes over time, and that many individuals in one population appear to match each other’s changes.
It takes a huge collective effort to gather enough data on these often-elusive animals to decode their complex songs, and what research has conclusively learned is that their ‘language’ is far more complicated than we expected. While there are many more questions to answer, what we have learned is enough to tell us that their capacity for learning and recalling complex calls with the associated meanings indicates much higher intelligence than previously thought.
Dolphins and toothed whales
It’s a similar story for the toothed whales – a group which includes whale species with any form of teeth or beak (like sperm whales), as well as all dolphins and porpoises. Like baleen whales, the toothed whales also produce long tones, humming or pulsing sounds, and whistles at frequencies necessary to carry the sound, though the distances needed to communicate are not necessarily as vast.
While the baleen whales are generally solitary and undergo annual migrations, toothed whales tend to travel in groups called pods, and do not usually travel over such large distances. Thus, communication between individuals and groups has adapted to these more social behaviours.
One notable feature of the toothed whale group is their use of echolocation. Echolocation refers specifically to the use of reflected sound to locate objects and discern surroundings, and dolphins are highly skilled at the use of echolocation to hunt and travel. In terms of discerning vocal acoustics, the most well-studied species in this group is the bottlenose dolphin, closely followed by orca. And just like nearly every study around cetacean acoustics, remarkable revelations are followed by even more questions.
Researchers have found that their acoustic ‘language’ is incredibly complex, including signature whistle sounds for individual animals (aka names), and variances in stereotypical calls between social groups akin to having a different ‘dialect’. They have even categorised sequences of calls specific to family groups which get passed down culturally. This presumably allows individuals to recognise and greet relatives if/when they cross paths in far corners of the world.
What does it all mean?
This complexity reflects a vast capacity for learning and communication, which again shows intelligence much higher than previously thought. In fact, it is now generally thought that bottlenose dolphins are second only to humans in intelligence. Studies have shown that they are capable of self-recognition, cultural learning, comprehension of symbol-based communication, and an understanding of abstract concepts and emotions. It makes you wonder what we could learn if we could somehow find a way to communicate in their language!
Hearing whales and dolphins in the Hauraki Gulf
Sometimes, on those lucky days when we have nice calm seas and a chatty, social group of common or bottlenose dolphins around our vessel, Dolphin Explorer, the crew will lower a hydrophone (a type of underwater microphone) into the water and connect it to the PA system. This allows our passengers to take a moment to appreciate the beautiful, unique, and mysterious language of these extremely intelligent creatures.
References
Dudzinski, K. M., Thomas, J. A., & Gregg, J. D. (2009). Communication in marine mammals. In Encyclopedia of marine mammals (pp. 260-269). Academic Press.
Sayigh, L. S. (2014). Cetacean acoustic communication. Biocommunication of animals, 275-297.
