Whales are mammals and possess hair, though it is highly specialized and unlike the fur coats of land animals. These structures are not the long, stiff “whiskers” associated with cats and dogs, but they serve a similar, highly sensitive sensory function in the aquatic environment. The presence of this hair, even in a vestigial form, is a remnant of their terrestrial ancestry. Their retention or loss is tied to the unique lifestyle of each species.
Whale Hairs: What They Are Called
The technical term for these specialized hairs is vibrissae, which are tactile sensory organs homologous to the whiskers found on nearly all other mammals. This nomenclature highlights their shared evolutionary origin and function as touch receptors. In most whale species, the vibrissae are significantly reduced, often becoming vestigial structures.
These sensory hairs are present in the fetal or neonatal stages of most cetaceans, underscoring their ancestral heritage. They are complex structures rooted in a specialized follicle richly supplied with nerves and surrounded by a blood sinus. This arrangement makes them highly sensitive mechanoreceptors, even if the hair is minute or shed shortly after birth. The scientific term for the suborder of baleen whales, Mysticeti, derives from the Greek word for “moustache,” perhaps reflecting early awareness of these facial hairs.
Sensory Function and Location
The primary role of vibrissae is to provide tactile sensory input in a fluid environment where visibility is often limited. They are effective at detecting minute pressure changes and subtle water movements. This allows the whale to perceive its immediate surroundings, which is important during feeding or navigating in murky waters.
In baleen whales (Mysticeti), the vibrissae are typically located around the jawline, on the rostrum (snout), and sometimes near the blowhole. Gray whales, for instance, have these small, stiff hairs concentrated on their heads to function as tactile sensors during their bottom-feeding process. The dense innervation of the follicle ensures that any disturbance of the hair shaft is immediately translated into a neural signal.
Hairs vs. Baleen: Clearing Up the Confusion
A common misunderstanding is confusing the sensory hairs with the baleen plates found in filter-feeding whales. The two structures are different in function, composition, and location. Baleen is a complex filter-feeding apparatus, not a sensory organ.
Baleen plates hang from the upper jaw and are made of keratin, the same protein that forms human fingernails and hair. These plates are used to sieve small prey, like krill and plankton, from large volumes of water. While baleen’s role is mechanical for feeding, vibrissae are sensory hairs embedded in the skin that function as sensitive touch receptors.
Variation Across Whale Species
The extent and utility of vibrissae vary between the two suborders of whales, reflecting their ecological niches and feeding strategies. Baleen whales (Mysticeti) generally retain some form of vibrissae into adulthood. Humpback whales, for instance, have prominent bumps on their heads and jaws called tubercles, and each houses a single sensory hair. These hairs are thought to help the whale sense prey density or water turbulence immediately in front of its mouth during lunge feeding.
Most toothed whales (Odontoceti), which use echolocation for navigation and hunting, largely lose their vibrissae shortly after birth. They often retain only the underlying sensory structure, known as a vibrissal crypt. However, some species in environments with poor visibility, like the Amazon river dolphin (boto), retain highly functional, stiff vibrissae on their snouts throughout their lives. These persistent whiskers help them probe the muddy river bottom and locate prey through touch and the detection of small movements.