How underwater animals communicate

Adélaïde Fouache

The underwater world has always been and always will be a big mystery for human kind. Everyday, marine biologists and scientists discover new things that open our eyes a bit more about what really is under the many seas, oceans, and rivers surrounding us.

Jacques Cousteau was a french naval officer, scientist, filmmaker, photographer, author, and researcher who studied the sea and all forms of life under water. He called the underwater world the “silent world”, but with time and research we have discovered that it is all but silent. Although we do have a lot of information about the communication methods of sea inhabitants, so many questions are still left unanswered today. We know that they do not communicate the same way we do, but they do have their own speaking methods and languages depending on the species.

What we know and hear thanks to underwater sonars, is that sound is the most efficient way to communicate. As sound travels far and effectively in the water, whales, dolphins, and killer whales all use sounds to get around, communicate, and hunt. Sound travels so well that even when members of a pod of killer whales are spread out over 150 square miles, a sound from one member will be heard by all of them. Those who have been observing them for years will tell you that they can recognize different sounds, sometimes even different ‘songs’ depending on the message they want to convey. For example, killer whales use echolocation and acoustic sounds when hunting, which sounds like clicking, that can last one or two seconds, and even up to ten seconds, depending on the subspecies of killer whales (e.g transient killer whales and southern resident killer whales). 

This clicking, called pulsed tones, is also used by dolphins, each click being different and conveying specific information. Similar to the killer whales, they use the clicking sounds for echolocation, waiting for the sound to come back to them if anything is in the way of the sound. Faster clicking sounds are used to convey anger, excitement or any other emotional state. Other than clicks, dolphins also communicate through pure tones, which are vocal signals, which sound like whistles, chirps, or screams. It is important to note that although many species of dolphins do use clicking or echolocation, it has been known and proven that some species do not use the clicking at all, but prefer another type of interaction. Despite researchers concluding that dolphins do not have a complex language and mostly repeat the same things, dolphin-lovers and experts often believe that there is more to this species than the research shows. Dolphins are very “talkative” animals, but they also communicate without using their “voice”, as when they slap their tail or their flippers on the water. This action can mean many things, ranging from getting the attention of another dolphin which is further away, to warning others of aggressive behavior from another animal, or even conveying that it is time to leave the area.

Whales also use sound to interact. An interesting fact about humpback whales is that they have one ‘song’ which is composed of repeated phrases of more or less than ten notes that can be sung for over ten minutes. Once the song is done, another humpback whale will answer by singing the exact same song. Although little is known about the meaning of these songs, we can appreciate the complexity of this communication. Breaching is another way whales communicate, meaning that parts of their body will go outside the water to slap it back inside. This can portray information about an emotional state, or a tactic during hunting.

But there are exceptions, as not all marine mammals use vocal signals to communicate, but instead use other senses equally as important for their survival. Although it has not been officially proven, there are theories that sharks use their sixth sense to communicate, mostly using body language, their hearing, and vibrations. No one has ever heard sound coming from sharks like we have from dolphins or whales, but it is possible that the frequency of their sound, if it exists, is out of human technology’s reach. The big difference between sharks and other animals discussed earlier is that sharks are more solitary creatures, hence why they may not have developed a complex communication system.

An animal that has hundreds of species and dozens of different types of communication is the fish. The following are examples of how some fish communicate,  but not all are able to communicate in these ways. It has been observed that certain species of fish can use, for the most part, any of their senses to communicate. One familiar example is synchronised swimming, in which they use gesture and motion to interact with each other. Some other species can smell or taste chemicals released by one of their members, or use electrical signals to communicate or locate their prey. Fish make sounds, for the same reasons as other marine animals (e.g foraging, communication, echolocation), but they are not using their mouth to create sounds, but rather they use their swim bladder instead.

Given that this is a condensed version of how underwater animals communicate, there are certainly many more species to learn about, and different ways in which they interact with each other. As more research is done on how underwater animals communicate, we will continue to gain a better understanding of their interactions with each other as well as any potential issues that may hinder their communication methods. 

Sources:  Australian Geographic, British Council, Dolphin Communication Project, New York Times