Why are baby whales and dolphins born with whiskers?

Vibrissae, commonly known as whiskers, are not exclusive to cats. They are present on the faces of most mammals. While we often associate these tactile hairs with our feline friends, cetaceans (i.e.: whales, porpoises, and dolphins) are also born with them. What could be the reason? Are these vibrissae useful? Let’s explore the fascinating world of cetacean vibrissae!

From land to sea: cetaceans’ evolutionary journey

Dolphins, along with whales and porpoises, belong to the cetacean family. These marine mammals have evolved from terrestrial ancestors over millions of years, slowly transitioning from a life on land to one in the ocean. During this remarkable transformation, cetaceans have kept some relics of their old life on land. One example includes cetaceans’ vestigial hips, the remnants of their ancestors’ hips and back limbs.

Scientists believe these vibrissae were inherited from their terrestrial ancestors. They may have acted as sensory organs when ancestral whales transitioned to living in the water, allowing these ancestors to perceive vibrations in the water.

Seals and sea lions are great examples of marine organisms that heavily rely on their whiskers. In their case, vibrissae are not just hairy appendages; they play a pivotal role in their lives, actively participating in foraging and locomotion.

A large diversity of whiskers between species

While most newborn toothed whales, (i.e.: dolphins, and porpoises), show a row of vibrissae on their rostrum (their snout), some species of baleen whales can show curious structures on their heads. Humpback whales can bear up to 50 of these structures called tubercles. Each tubercle has a hair in the middle and is connected to nerves – around 400 of them. Some of these nerves might sense changes in pressure or water movements.

Bowhead whale newborns also show patches of vibrissae on their chin, rostrum, and close to their blowholes. Since baleen whales do not use echolocation, these small vibrissae or tubercles might help them navigate their first weeks in the water.

Are whiskers useful to cetaceans?

In their early stages of life, whales and dolphins can use their vibrissae for crucial functions such as staying close to their mothers, recognizing individuals, and locating the mom’s nipple for feeding. Dolphin calves only start to use echolocation after a couple of weeks. To do so, they emit high-frequency clicks into the water and interpret the returning echoes to navigate, locate prey, and communicate. But before using this impressive skill, they might have to rely on their vibrissae to navigate their new environment.

However, as they grow up, cetaceans’ whiskers disappear. After shedding their whiskers, individuals retain a continuous line of minuscule cavities called ‘vibrissal crypts’ throughout their entire lifespan. These may play a different role, possibly helping the adults sense the movement of water and the position of their heads.

Some scientists even suggested that these structures might be used for electroreception in some species of dolphins, which involves the detection of electrical signals in the environment. For dolphins foraging in muddy environments like the Guiana dolphins, electroreception could help them detect fish movements in the sediment.

Can adult dolphins have whiskers?

In certain adult river dolphins, like the pink Amazon river dolphin, keeping the vibrissae on their snouts can act like a built-in tool to help them find food in the murky Amazon River. in this case, their vibrissae sense changes and movements, possibly helping them locate fish, especially when they’re digging in the mud.

Sources and further reading

• Mynett, N., Mossman, H. L., Huettner, T., & Grant, R. A. (2022). Diversity of vibrissal follicle anatomy in cetaceans. The Anatomical Record, 305 (3), 609-621.
• Czech-Damal, N. U., Liebschner, A., Miersch, L., Klauer, G., Hanke, F. D., Marshall, C., … & Hanke, W. (2012). Electroreception in the Guiana dolphin (Sotalia guianenCzech-Damal, N. U., Liebschner, A., Miersch, L., Klauer, G., Hanke, F. D., Marshall, C., … & Hanke, W. (2012). Electroreception in the Guiana dolphin (Sotalia guianensis). Proceedings of the Royal Society B: Biological Sciences, 279(1729), 663-668.sis). Proceedings of the Royal Society B: Biological Sciences, 279(1729), 663-668.
• Bauer, G. B., Reep, R. L., & Marshall, C. D. (2018). The tactile senses of marine mammals. International Journal of Comparative Psychology, 31.

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