Gene researchers have discovered that penguins' taste palate may be severely limited to the point that they do not even have the receptor for their primary prey.
According to the Guardian, authors of a study published in the journal Current Biology based their discovery on observations of Adelie and Emperor Penguins. Standing out the most was the absence of an umami taste gene, which is associated with fish.
"The lack of taste buds strongly suggests a reduction in taste function," the researchers wrote in their study. "Taken together, our results strongly suggest that the umami and bitter tastes were lost in the common ancestor of all penguins."
Vertebrates have five taste genes known as sweet, umami, bitter, sour and salt, but the researchers found penguins to only have those last two.
"Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don't have them," study lead author Jianzhi Zhang, a professor in the University of Michigan's Department of Ecology and Evolutionary Biology, 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."
Co-authoring the study was Huabin Zhao, a postdoctoral researcher of Zhang's, and Jianwen Li. The researchers are not sure if this lack of taste preceded an evolutionary change where penguins' tongues became rough and thick in order to better hold fish.
"This give us a hint, perhaps, that this loss of taste genes has something to do with the inability of this protein to work at lower temperatures," 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."
