Penguins Only Have Bitter And Salty Taste Receptors
Scientists have discovered that penguins only have the ability to taste salty or sour food. According to the results of a genetic study the flightless bird lost three of the five basic tastes a long time ago as a result of evolution. Taste is vital for survival in most animals but may not be that important for penguins which tend to swallow fish whole say researchers.
Most birds cannot taste sweet
Many other species of bird lack the ability to taste sweet things but they do have the receptors to detect umami (meaty) or bitter flavours. The discovery came when researchers began to decode the genome of the penguin and found there were some taste genes missing. The behaviour of swallowing food whole and the structure and function of their tongue suggests that penguins do not require the perception of taste. A closer look at penguin DNA showed that all species of this animal do not have functioning genes for bitter, sweet and umami tastes.
“Based on genetic data, penguins are believed to have sour and salty tastes, but have lost sweet, umami, and bitter tastes,” lead researcher Prof Jianzhi Zhang, of the University of Michigan, US, and Wuhan University, Chin said.
Penguins swallow fish whole
The taste of umami gives food the strong savoury flavour that people associate with meat. Not having this sense is very surprising for an animal that is carnivorous. However it would seem it is unimportant for the penguin which tends to swallow fish without chewing. The researchers however remain unsure whether these traits are a cause or consequence of loss in taste.
Loss of taste is a puzzle
Prof Zhang published his findings in the Current Biology journal and says they are a puzzle. One possible clue comes from the evolution of the penguin on Antarctica’s frozen ice sheets. At very low temperatures, sending signals from bitter, umami, and sweet to the brain does not work, though it does work for salty and sour. This may have been the impetus for the species to gradually lose its sense of taste the researchers reckon. What is very interesting, with the exception of the humming bird which feeds on nectar, almost all other species of bird cannot taste sweet.
