Penguins, iconic birds of the Southern Hemisphere, possess small, slit-like openings called nares on their beaks. These nares serve a similar purpose to a human nose, enabling both breathing and a surprising sense of smell.
Penguin Nostrils and Breathing
Penguin nostrils are small, slit-like openings on either side of their beak, often positioned near the base. These nares are the entry points for air, allowing penguins to breathe oxygen from the atmosphere using their lungs. Penguins cannot breathe underwater and must surface regularly to take in air.
When a penguin dives, its nostrils are adapted to close, preventing water from entering its respiratory system. Some species, like Emperor penguins, can hold their breath for over 20 minutes and reach depths of hundreds of meters. Their respiratory system, which includes lungs and multiple air sacs, efficiently extracts and utilizes oxygen during these deep and prolonged dives.
A unique adaptation in penguins and other marine birds is the presence of supraorbital glands, also known as salt glands. These glands, located above their eyes and connected to the nasal passages, filter excess sodium chloride from the bloodstream. This salt accumulates when penguins ingest saltwater, primarily through their prey. The concentrated brine then drips out of the nostrils, often appearing like a runny nose as the penguin shakes its head to expel the salty fluid.
The Penguin Sense of Smell
Recent scientific investigations reveal that penguins possess a functional and important olfactory sense. Penguins are evolutionarily related to tube-nosed seabirds, a group known for their acute sense of smell, suggesting a shared capacity for olfaction. This sense plays a role in several aspects of their lives, particularly in their marine environment.
One significant way penguins use their sense of smell is in foraging for food. Research indicates that penguins are attracted to dimethyl sulfide (DMS), a chemical compound released when krill consume phytoplankton in the ocean. This ability allows them to locate productive feeding grounds across vast expanses of open water. Studies on African penguins, for instance, demonstrate their sensitivity to DMS, indicating its importance in their feeding strategies.
Beyond finding food, olfaction also aids penguins in navigation and social recognition. They use scent cues to navigate back to their colonies from the open ocean and to locate specific areas or groups within crowded nesting sites. Furthermore, studies on Humboldt penguins suggest they recognize kin through smell, helping to prevent inbreeding. King penguins have also shown responses to the scent of feathers and feces, which could facilitate individual recognition among mates and offspring.