While humans gear up for holiday feasts and sweets galore, many might be wondering if penguins enjoy special treats during the holidays.
The penguins don’t have dessert on holidays—or any other day—and they wouldn’t actually be able to taste the difference anyway. That is because penguins cannot detect sweet tastes. In fact, penguins do not have the ability to taste sweet, umami (meaty), or bitter tastes!
Most vertebrates can detect the following five basic taste qualities: sweet, umami, bitter, sour, and salty. A 2015 genetic study revealed that out of those five taste qualities, penguins can detect only sour and salty tastes (here’s a BBC News summary of the study). Researchers have been able to identify the gene sequences associated with those taste qualities and determined that those sequences are absent in the penguin genome.
Penguins eat their fish whole and don’t waste any time chewing their food like humans do. Instead of teeth, penguins have papillae (rear-facing spines or fleshy ridges) inside of their mouths that are specialized to allow them to swallow live fish whole. A 1998 study did not find any taste buds located in the mouths of four individual penguins of different species. Since most taste receptors are located on taste buds, it is suggested that taste is not a main function of penguin mouths.
While it might seem unusual that penguins, which are carnivorous animals, lack umami (meaty) taste receptors, they actually do not rely on taste because of how quickly they eat their food. It is suggested that penguins primarily rely on visual cues for foraging as they lack those three taste receptors, and their olfactory senses are less developed than that of other water birds.
The loss in taste functions over time is likely due to their origins from the Antarctic and the cold weather there as sweet, umami, and bitter taste receptors have decreased function in lower temperatures. Umami and bitter tastes are thought to be lost in the common ancestor of penguins (estimated between 10 million and 20 million years ago), and sweet taste was likely lost prior to that. Even though not all penguins live in snowy and icy climates, these taste functions have not been regained, and penguins are able to carry on without them.
Come watch our penguins chow during our daily feedings at 9 a.m. and 2:30 p.m.! If you are 18 or older, you can even apply to volunteer or intern in the penguin exhibit. Check out our volunteer opportunities here!
– Shannon Freyer, Assistant Aquarist