Penguins That Love Fish Might Not Know Their Taste

Penguins might have lost the ability to recognise sweet, bitter and meaty flavours long time ago, say Huabin Zhao and team in a study published in Current Biology. A genetic study at the University Of Michigan reports that the penguins could have lost sweet, bitter and savoury, meaty flavour known as umami but might know the sour and salty tastes.

The researchers found the taste genes missing in penguins when they decoded the bird’s genome. When studied closely, it was found that all the penguin species lacked the receptors for sweet, bitter and umami tastes. All the other neighbouring genes were present intact, except for the taste receptor gene. Therefore, there is no possibility of errors in the quality of genome sequencing, said lead researcher Prof Jianzhi Zhang of the University of Michigan, US, and Wuhan University, China.

The salt receptor genes found in the penguins don’t matter much as they are very much essential for the kidneys to function. If they weren’t present, they would be “dead penguins,” said David Yarmolinsky, a taste researcher at Columbia. He also added that therefore, the presence of the salt receptor gene doesn’t mean that the penguins have salt-tasting ability in their tongue. The penguins should be fed with something sour to find out if they can recognise the sour taste, specified Yarmolinsky.

Absence of umami receptors in a carnivorous animal like penguin is surprising, but that doesn’t matter much as the penguins swallow the fish without chewing. The swallowing behaviour and the structure and function of their tongue suggest that there is no need for taste perceptions in penguin, said Zhang. He also said that it is unclear if these traits are cause or a consequence of the loss of taste. This research supports some of the recent predictions that sensory receptors are adaptive to animals’ lifestyle, said Yarmolinsky.

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