Sound in the Sea: Why Whales "Talk"

Water transmits sound roughly four to five times faster than air, and unlike light, sound travels effectively across vast ocean distances. For whales — air-breathing mammals living in a world where visibility is often limited to metres — sound became the primary channel for navigation, finding prey, and communication. Over millions of years of evolution, cetaceans (whales, dolphins, and porpoises) developed extraordinarily sophisticated acoustic abilities that continue to astonish researchers.

Types of Whale Sounds

Whales produce several fundamentally different types of sounds, each serving distinct functions:

Clicks

Toothed whales (odontocetes), including sperm whales, dolphins, and orcas, produce rapid clicks using specialised structures in their nasal passages. These clicks are used for echolocation — by listening to the returning echo, a whale can build a precise three-dimensional picture of its environment and locate prey in complete darkness. Sperm whale clicks are among the loudest sounds produced by any animal.

Whistles and Burst-Pulse Sounds

Dolphins and some other toothed whales produce whistles and complex burst-pulse sounds used in social communication. Bottlenose dolphins develop individual signature whistles — unique calls that function similarly to names. Dolphins use each other's signature whistles to address specific individuals, a form of referential communication rare outside of humans.

Songs

Baleen whales (mysticetes), which lack teeth and feed by filtering, produce the most structurally complex vocalizations. Humpback whale song is the most studied: only males sing, and their songs consist of repeating phrases arranged into themes. Songs last from minutes to hours and evolve progressively throughout a breeding season — all males in a population singing essentially the same song, which changes in coordinated fashion over time. The mechanism by which this cultural transmission occurs across populations remains an active area of research.

The Low-Frequency World of Blue and Fin Whales

Blue whales and fin whales communicate using calls so low in frequency (below the threshold of human hearing without equipment) that they travel across entire ocean basins. Blue whale calls can be detected by underwater hydrophones at distances of hundreds to potentially thousands of kilometres under the right oceanic conditions. Scientists believe these ultra-low-frequency calls may serve to maintain contact between widely dispersed individuals and to facilitate mate finding across vast expanses of open ocean.

Orca: Dialects and Culture

Killer whales (orcas) present a particularly compelling case for cetacean culture. Different populations — called ecotypes — have distinct dietary specialisations, behaviours, and acoustic repertoires. Within populations, distinct family groups (pods) have their own recognisable dialects: sets of calls that differ subtly from those of neighbouring pods. These dialects are learned, not innate, passed from mothers to calves through social interaction. Research on orca dialects has provided important evidence that complex cultural transmission is not unique to humans among animals.

How Scientists Study Whale Communication

Researchers use several methods to investigate cetacean acoustics:

  • Hydrophone arrays: Networks of underwater microphones deployed at fixed locations or towed behind research vessels, allowing scientists to record and locate calling whales.
  • Acoustic tags: Small devices temporarily attached to whales using suction cups, recording sound from the whale's perspective and tracking its movement and dive behaviour.
  • Machine learning: Computer algorithms trained on large acoustic datasets can now detect and classify whale calls with high accuracy, enabling large-scale analysis of previously unmanageable recording archives.
  • Photo-identification and network analysis: Matching acoustic data to identified individuals allows researchers to understand who is communicating with whom and in what social context.

What We Still Don't Know

Despite decades of research, fundamental questions remain open. Do whale vocalisations constitute a language in the sense of having compositional syntax — where meaning is built from the combination of smaller units? Current evidence suggests cetacean communication is rich and contextually flexible, but whether it reaches the structural complexity of human language remains debated.

Recent projects using artificial intelligence to analyse vast libraries of whale recordings aim to detect previously unrecognised structural patterns in cetacean calls. The coming decades of research may substantially revise what we think we know about animal communication — and our own place in the spectrum of communicating minds.

Why This Matters for Conservation

Understanding whale communication has direct conservation implications. Anthropogenic ocean noise — from shipping, sonar, and industrial activity — overlaps with the frequency ranges whales use to communicate and navigate. Research into whale acoustics helps scientists assess how noise pollution disrupts communication, feeding, and reproduction, informing regulations and conservation planning to protect these remarkable animals.