Penguins have been making headlines all day thanks to the publication of a scientific study that showed they lack tastebuds for umami, which would allow them to taste the fish they eat. (Nor can they detect sweetness or bitterness, but that fact is less salient given their limited diets.) Indeed, nearly a quarter of penguin species (4/17) lack any tastebuds at all.
If you accept the theory that organisms evolve a sense of taste to reward them for eating the right thing, and thereby incentivize them to do it again, the absence of umami tastebuds is somewhat puzzling: how do fish know what to eat? The scientists who conducted the study do not offer any definitive conclusions, but do suggest a few possibilities:
One. Umami genes don’t work well in the cold, and “it’s about zero degrees (C) when you eat cold fish.”
Two. Penguins have spiky tongues (to help grip their prey), which impairs their ability to taste anything.
Three. Penguins can tell their food is nutritious by watching it swim around, and need no further feedback to decide what is edible.
I would like to offer my own theory, based on common knowledge regarding penguin parenting practices:
The adult penguin will partially digest the fish or other food inside their stomachs. This usually takes several hours. When the food has been digested enough, the penguin coughs the food back up and feeds it to the chick by pouring the mixture into the chick’s beak.