Hello! Why Did Penguins Evolve To Have Black Feathers If They Live In Icy (mostly White?) Locations?

Hello! Why did penguins evolve to have black feathers if they live in icy (mostly white?) locations? I understand them having a white tummy because when swimming they could be more difficult to identify by a predator swimming below them? Thanks!

Love your blog!

Hello! So, here's what I learned at uni:

the widely-accepted reason penguins have black feathers is the same reason they have white tummies, but backwards. When swimming, they are more difficult to identify by a predator swimming above them! You can see similar countershading in sharks and dolphins, and also on land animals like mountain goats and lizards. Overall, it helps to make animals less obvious when viewing from the side, because it reduces the obviousness of their shadow.

Hello! Why Did Penguins Evolve To Have Black Feathers If They Live In Icy (mostly White?) Locations?

As to why penguins have black feathers in icy, mostly white, locations (on LAND), you need to consider why it would be good to be white in an icy, white location in the first place!

Mostly, it would provide camouflage, which would protect from land predators! However, penguins don't really have any significant land predators in Antarctica. There are no polar bears, or big snakes, or even foxes or coyotes in Antarctica, so the penguin won't benefit from being camouflaged on land. Basically, there's no "selective pressure" for them to be all white!

some penguin chicks, however, do have to worry about a few predators, so they have a little more camouflage than the adult penguins:

Hello! Why Did Penguins Evolve To Have Black Feathers If They Live In Icy (mostly White?) Locations?

What's more, there are likely advantages to black feathers in a cold environment like Antarctica! For example, in the sun, dark feathers absorb more thermal energy, helping to warm the penguin and maintain their body heat.

There may also be some stuff with black feathers being more resistant to wear/ friction drag in the water, but that's entering the realm of ongoing research, which I won't get into here.

Let me know if there's anything that needs clarifying!

(some citations if anyone wants further reading:)

Bonser, R. H. (1995). Melanin and the abrasion resistance of feathers. The Condor, 97(2), 590-591.

Ksepka, D. T. (2016). The penguin's palette--more than black and white: this stereotypically tuxedo-clad bird shows that evolution certainly can accessorize. American Scientist, 104(1), 36-44.

Rowland, H. M. (2009). From Abbott Thayer to the present day: what have we learned about the function of countershading?. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1516), 519-527.

Zagrai, A., & Hassanalian, M. (2020, July). Penguin coloration affects skin friction drag. In 2020 Gulf Southwest Section Conference.

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‘Wrinkles’ in time experience linked to heartbeat

How long is the present? The answer, Cornell researchers suggest in a new study, depends on your heart.

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The research builds evidence that the heart is one of the brain’s important timekeepers and plays a fundamental role in our sense of time passing – an idea contemplated since ancient times, said Adam K. Anderson, professor in the Department of Psychology and in the College of Human Ecology (CHE).

“Time is a dimension of the universe and a core basis for our experience of self,” Anderson said. “Our research shows that the moment-to-moment experience of time is synchronized with, and changes with, the length of a heartbeat.”

Saeedeh Sadeghi, M.S. ’19, a doctoral student in the field of psychology, is the lead author of “Wrinkles in Subsecond Time Perception are Synchronized to the Heart,” published in the journal Psychophysiology. Anderson is a co-author with Eve De Rosa, the Mibs Martin Follett Professor in Human Ecology (CHE) and dean of faculty at Cornell, and Marc Wittmann, senior researcher at the Institute for Frontier Areas of Psychology and Mental Health in Germany.

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“These observations systematically demonstrate that the cardiac dynamics, even within a few heartbeats, is related to the temporal decision-making process,” the authors wrote.

The study also showed the brain influencing the heart. After hearing tones, study participants focused attention on the sounds. That “orienting response” changed their heart rate, affecting their experience of time.

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“Even at these moment-to-moment intervals, our sense of time is fluctuating,” he said. “A pure influence of the heart, from beat to beat, helps create a sense of time.”


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