Penguins Have Bad Taste

Penguins can only taste two flavors, salty and sour, according to new research that sheds light on why temperature is so important to food appreciation.

There is no such thing as a food connoisseur penguin, suggests new research that found penguins can't taste savory or sweet flavors.

For the flightless, waddling birds, foods come in just two flavors -- salty and sour -- according to the new study, which is published in the latest issue of the journal Current Biology.

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"Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don't have them," co-author Jianzhi "George" Zhang of the University of Michigan said in a press release. "These findings are surprising and puzzling, and we do not have a good explanation for them. But we have a few ideas."

Zhang and colleagues made the determination after sequencing the genomes for Adelie and emperor penguins. The researchers were surprised that they couldn't find some basic taste genes, so they took a closer look at penguin DNA.

This led the scientists to conclude that all penguin species lack functional genes for the receptors of sweet, umami and bitter tastes.

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You might think that's obvious, because penguins aren't exactly noshing on candy or umami-laden soy sauce. But the reason for the loss likely has more to do with temperature than what the penguins are eating. The clues for this are the missing taste receptors themselves.

Those for sweet, umami and bitter flavors are temperature sensitive. They don't work well, if at all, if the individual is eating cold food in a cold environment. That's one reason why people can't taste the flavors in ice cream very well after a while. The cold dampens their taste buds, as well as ability to smell, a bit.

Penguins or their ancestors probably had all of the usual taste receptors at one point, but lost them when they moved to cold environments. Some penguins have since moved to warmer areas, but because all penguins trace their roots to Antarctica, penguins the world over are still hardwired, taste-wise, for eating in a colder habitat.

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The researchers further suspect that penguin tongues, with their sharp papillae appendages, are built more for grabbing onto slippery food than tasting edibles.

Before you feel too sorry for penguins, remember that they swallow their food whole. It's not as though they're going to swish fishmeal in their mouths a/la a wine aficionado in hopes of detecting different flavors.

Zhang said, "Their behavior of swallowing food whole, and their tongue structure and function, suggest that penguins need no taste perception, although it is unclear whether these traits are a cause or a consequence of their major taste loss."

Photo: Emperor penguins. Credit: John Landis/NSF, Wikimedia Commons

Penguins! Unlike the dodo, this flightless bird has figured out how to make a go of it, capturing our hearts into the bargain. With winter well underway, and a historic blizzard pummeling the east coast as we speak, what better time to chill with some pictures of penguins? Enjoy these amazing creatures!

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Once waterbound, penguins are fantastic swimmers that can zoom through the ocean at some 15 to 20 miles per hour.

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There are 18 species of penguin, ranging in size and even color.

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Some penguins receive checkups from tiny robot penguins. This remote-controlled fake penguin's job is to read radio tags placed by researchers on actual penguins.

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A penguin couple holds hands, or flippers. Penguin couples are monogamous during mating time.

It can vary a bit by species, but wild penguins can live from 15 to 20 years or so.

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Emperor penguin siblings take in the scenery. The Emperor is the largest species of penguin. When these two grow up they'll weigh around 75 pounds and stand about 3 feet 7 inches tall.

Emperor penguin chicks will begin to fledge once they hit about half their adult size.

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This nest has a mouth to feed. Penguins eat krill, fish, squid and other types of marine life they can fetch while underwater.

This African penguin, found on the continent's southwestern coast, is also called a jackass penguin, although it won't answer to that name.

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Penguins are quite nearsighted when on dry land. It's underwater where their vision really steps it up. There, they can really hone in on the colors of the ocean such as blue or violet. Such eyesight helps them avoid being eaten by killer whales or leopard seals, their chief predators of the deep.

King penguins, that is. They're the second-largest penguins, after the Emperors.

Penguins do enjoy a crowd. The Southern hemisphere wins the penguin population census. It's tempting to think penguins mostly hang out in Antarctica, but they're actually all over the lower half of the planet, and further north than you might guess. From islands in the South Pacific, to Australia, New Zealand, South America and South Africa, you can find penguins making a living. There are even three species that call places as far north as the Galapagos Islands home.

Should this gang on the ferry ride decide to go for a swim, they could stay underwater for about 15 to 20 minutes and go as deep as nearly 300 feet (91 meters).