The question of what a whale smells like is a complex scientific puzzle, involving the anatomy and evolutionary adaptation of these marine mammals. The capacity for smell differs dramatically across species, and the odors humans encounter at sea are often not the animal itself. Instead, the smell usually comes from the expulsion of air and waste products resulting from the whale’s immense size and feeding habits.
The Olfactory System in Whales
The capacity for smell, or olfaction, varies significantly between the two major groups of whales: toothed whales (Odontocetes) and baleen whales (Mysticetes). This difference results from their divergent evolutionary paths and specialized feeding strategies.
Toothed whales, including dolphins and sperm whales, have largely abandoned the sense of smell. Odontocetes generally lack the anatomical structures necessary for a functional sense of smell, such as the olfactory bulb, making them functionally anosmic (unable to smell). Their nasal passages were repurposed for producing the high-frequency clicks used in echolocation, a superior sensory tool for hunting underwater.
In contrast, baleen whales, like humpback and blue whales, retain a more complete, though reduced, olfactory system. They possess some olfactory nerve tissue and receptor genes, suggesting a limited capacity to smell. Since olfactory tissue requires exposure to air for detection, baleen whales likely use this sense primarily when they surface, inhaling airborne molecules when they blow.
Scents Emitted by Living Whales
When humans encounter a whale, the most common odor comes from the phenomenon known as “whale blow” or “whale breath.” This is the forceful expulsion of air, mist, and water vapor from the blowhole when the whale surfaces. The smell is not fresh air, but a pungent cloud containing biological residue.
This expelled air is laced with bacteria, oils, and partially digested food particles from the respiratory tract. The resulting odor is often described as fishy, oily, or sulfurous, depending on the whale’s recent diet. Humpback whales feeding on krill, for example, can produce a strong, slightly rancid smell. The common nickname “stinky minke” highlights the notoriety of this fishy exhalation.
Other odors are associated with the whale’s waste. Whale feces, particularly from krill-eating species, can be highly concentrated and float near the surface, sometimes described as having a strong, musky smell. A different, highly prized scent is ambergris, a rare, waxy substance excreted by some sperm whales. Ambergris initially smells like manure but cures over time to develop a sweet, earthy fragrance used in perfumery. The smell of a deceased whale, by contrast, is intensely rancid and oily, derived from the breakdown of its massive blubber layer.
How Whales Use Chemical Senses
Even with a reduced or absent sense of smell, whales utilize chemoreception to interact with their environment. This broader chemical sense allows them to detect dissolved compounds in the water, effectively “tasting” the ocean. This ability is distinct from traditional olfaction, which relies on airborne molecules.
Chemoreception is useful for baleen whales in locating patchy food sources, such as krill aggregations. Certain species show behavioral responses when exposed to chemicals like krill extract, suggesting they can sense these food-related cues over distances. They may also detect dimethyl sulfide (DMS), a chemical released by phytoplankton, which acts as a marker for high-productivity feeding areas.
While toothed whales lack structures for smell, some research suggests they may possess a form of “quasi-olfaction,” using nerves like the trigeminal nerve to detect certain chemicals. This ability to sense dissolved chemicals assists in navigation, identifying feeding grounds, and potentially facilitating short-range communication. This functional adaptation compensates for the loss of a traditional sense of smell.