It Appears Penguins Have No Taste

PENGUINS are among the world’s most dedicated seafood eaters. But they can’t taste fish, biologists have discovered. The Penguin Post has learned that Chinese and American researchers have found that the flightless birds have only two of the five basic tastes — salty and sour — after losing the capacity to detect sweet, bitter and “umami” or savoury flavours.

Jianzhi Zhang, a genomic evolutionist at the University of Michigan, said the results were surprising. “Penguins eat fish, so you would guess they need the umami receptor genes,” he said. The discovery, revealed in the journal Current Biology, adds to the taste limitations known to bedevil some of the world’s most loved and loathed creatures. “Whales and dolphins have lost all tastes except salty,” Professor Zhang told The Australian. “Vampire bats have lost sweet and umami tastes.”

Adelie penguins and their water-going cousins can’t taste their prey’s fishy flavour, scientists have found.

Adelie penguins and their water-going cousins can’t taste their prey’s fishy flavor, scientists have found.

Birds also lack receptors for sweet flavors, even though many eat fruit and nectar. Scientists believe birds lost the T1R2 gene — which is crucial for tasting sugar — sometime during or after their evolution from meat-eating dinosaurs. The latest study found that receptors for detecting bitter and savory tastes were also missing from the genomes of Adelie and emperor penguins. Subsequent research revealed the other 15 penguin species also lacked these genes.

The researchers believe another key gene, known as TRPM5, may have effectively been frozen out of the genome of living penguins’ most recent common ancestor during an evolutionary stint in Antarctica. TRPM5 is “temperature-sensitive” and doesn’t function properly when things “get really cold”, the journal reported. While some penguins now inhabit warmer latitudes, all penguin species trace their roots to the frozen continent. But the study has raised a chicken-and-egg question, with the researchers unsure if penguins swallow fish whole because they can’t taste them, or vice-versa. Anatomical studies have found that penguins’ tongues are covered by a thick layer rather than taste buds, suggesting they’re used to catch food rather than taste it. “Their tongue structure and function suggest that penguins need no taste perception,” Professor Zhang said. “It is unclear whether these traits are a cause or a consequence of major taste loss.

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