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#countershading
learnyouabiology · 1 year
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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.
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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:
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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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fundinofactoftheday · 2 years
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Dinofact #32
Sinosauropteryx, first described in 1996, was the first dinosaur outside of Avialae (birds and immediate relatives) to be found with direct evidence of feathers. Additionally, fossils of Sinosauropteryx preserved pigmentation, showing direct evidence that the dinosaur had a dark and white banded tail, and possibly displayed countershading, that is, it had a lighter belly and darker back.
Source: wikipedia
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uwmspeccoll · 1 year
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Science Saturday
There are a plethora of prominent examples of the mutual influence between the arts and sciences: Leonardo De Vinci, Albert Einstein, Maria Sibylla Merian, Hedy Lemarr, Geothe. The painter behind today’s Science Saturday offering, Abbott H. Thayer, did indeed make some lasting contributions to natural science, most notably on the role of countershading nature, sometimes referred to as Thayer’s Law, and on disruptive patterning. His writings on animal camouflage were influential in the development of tactical camouflage during World War I, urged on by Thayer himself.
Published in New York in 1909 by Macmillan, Concealing-Coloration in the Animal Kingdom: An Exposition of the Laws of Disguise Through Color and Pattern: Being a Summary of Abbott H. Thayer’s Discoveries was the culmination of Thayer’s work on the subject. Authorship is credited to Gerald H. Thayer, with his father Abbott H. Thayer’s contributing an introductory essay and many of the illustrations. The elder and younger Thayers collaborated extensively on the book, which was printed in New York at The Trow Press, with lithographs and half-tone prints by A. Hoen & Co. of Baltimore. 
Despite the aforementioned lasting contributions, the book received scathing criticism from the scientific and naturalist community, including being roundly mocked by Theodore Roosevelt. While some of Thayer’s observations were sound, he insisted that every aspect of animal coloration was rooted in camouflage, a theory that lacked scientific rigor. Take the example of the flamingo (illustrated in the final image above): Thayer argues that their vibrant plumage is camouflage because, for a brief period during sunrise and sunset, the animals might appear to blend into the horizon when viewed by predators from below the water line. There is no attempt to explain how their bright pink hue might help them escape predation for the other 23 or so hours of the day.
Explore more Science Saturday posts here.  
-Olivia, Special Collections Graduate Intern
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skulldox · 1 year
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Green Kobold
Just a quick drawing I threw together. Like how the shapes turned out.
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ardenrosegarden · 2 years
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This is Hoffman's mosasaur, the ocean’s deadliest predator; but he’s not here to eat, he’s come to be cleaned. Mosasaurs are giant lizards and have both a lizard’s forked tongue and, during the mating season, a lizard’s colorful skin. Now it’s time to shed old skin. And when you need to look your best, nothing but an all-over body scrub will do. Fish, shrimp, pick the scales shed from his body. Resting at the surface allows this sea-going, air-breathing lizard to fill his lungs and relax.
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kaiserouo · 3 months
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I'm playing way too much pvp with my warlock someone please save me
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melanorhynchus-side · 3 months
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ishmael orca! your ishmael orca!
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there is no scarier cetacean than a new yorker
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bonus i had to give her 5 fingers so she could still flip people off
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despazito · 7 months
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Paleoart ppl imho get too uppity about artists reusing certain patterning and colourations as if you don't see multiple extant species currently rocking the same look
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transingthoseformers · 4 months
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Welcome to the Whalesnake Leviathan!
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At a whopping 136 meters, it's pretty fucking big (admittedly it is mostly long rather than big considered how skinny it is), with a large head containing somewhere around 58 needlelike teeth.
The two long sensory crests help it detect chemical changes in the water, as it's highly sensitive to changes in the water quality. I suggest this as both a cool little ecology thing and something the player can use to scare the Whalesnake leviathan away from their ship with a toxin attack (like the gas balls in the first subnautica game!)
The Whalesnake leviathan is primarily an ambush hunter, lying in wait in the pitch black darkness. I like to think it's capable of short bursts of incredible speed thanks to the disproportionate wing-fins but relatively weaker tail, and that in a hypothetical situation the player's ship might be able to out stamina it.
I'm very tempted to suggest that it eats prinarily smaller leviathans / large leviathan adjacent fauna. Also tempted to suggest the bioluminescent spots and sensory crests only glow when it's getting ready for a charge or in "hunting" mode as a visual indicator for the player.
Considering how fucking itty bitty the eyes are, I'm imagining it has very poor eyesight and hearing, mostly hunting via a very strong sense of smell and smell adjacent senses. It glows because glowing seems to be a ancestral trait on planet 4546B
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felassan · 1 year
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some quick'n'dirty thoughts on the new Codex entries:
[wild speculation] it feels like the Grand Necropolis is a game location we will visit (it also comes up quite a bit in the wider blogpost). and/or we'll have a Mortalitasi companion
I'd guess that the writer of this codex, and their friend that teases them, are the two characters that feature in the short story from Dragon Age Day last year, The Flame Eternal. Emmrich referring to Johanna? (Or just emmrich and someone else.. wouldn't really make sense for a nevarran to tease their nevarran friend about their own practises, on reflection). both that short and this new codex are by Sylvia, and the shade of cyan used to obscure the diary owner's name is similar to the cyan in the short story art. saying that, it's the same cyan as Skeleton Boi has, and seems to sometimes indicate necromancy & related magic generally speaking
I could've missed em, but I had a lil look and couldn't find the referenced writings of Genetivi's here or in the WoTs, so they must be among his many in-world writings that we the players haven't seen (it'd be so good to sit in an an in-world library and read and read and read..!!! literally the dream.). but if I missed them pls lmk :D
Vinsomer. the Last Court/Serault enthusiast in me wonders if the lecturer giving the talk on Vinsomer is Frederic of Serault, Professor of Draconology from the University of Orlais. Vinsomer can swim! makes sense, we meet one in DA:I on the Storm Coast and the lore says they prefer rocky coasts.
Thedas has orcas confirmed~ when an animal is dark dorsally and light ventrally, it's called countershading. it's a method of camouflage. in orcas this helps hide them from their prey. there's a squidlike creature on this version of the map, and the "big worms that burrow near the shore" remind me of thresher maws from ME. Thedas has giant bobbit worm type things on the beaches?? 😭 electric eels stun their prey by generating electricity, and it makes sense that a big creature that hunts in the sea would have a beak-like mouth like squid do. the biologist in me is pleased by these references and the thought that clearly went into this codex :D
what's attacking Vinsomer/her lair/her young and why is it a mystery? it's probably because I was thinking about the red lyrium skeleton guys again today just before the community update post came out (literally ten-fifteen mins or so before the blogpost aaaa), but the new Vinsomer codex reminds me of this excerpt [bottom one] for some reason: "From eyewitness reports, the adult dragons never ventured close to where the red lyrium grows, even though they could easily have done so. I can only conclude that the creatures instinctively understand that red lyrium poses a threat."
skskshfuehufh the double entendres in the Randy Dowager codex. Genetivi you rogue
and more generally speaking, this part of the blogpost:
The Hero of Ferelden. The Champion of Kirkwall. The Herald of Andraste. Each of them marked their legacy in the annals of history, but time marches forward and the age of these heroes cannot last forever. As a friend of ours once said, “it’s time for a new hero."
has me wondering for the 89898th time what the DA4 PC's title will be if any. the what of what??? :D I'm dyin. I wonder if time marching forward ties to the implied timeskip to 9:52, and it's exciting to know that there will be other upcoming community updates like this, with the next one being focused on Design. hope the next one contains some new Codex entries too! 👁
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garblegarden · 6 months
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adding countershading can instantly spice up any character's design
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wolves-facts · 4 months
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The gray wolf is one of many animal species that commonly exhibits countershading, a pattern where the top of the body is darker than the underside. This is usually thought to be a form of camouflage, counteracting the natural form shadow on an animal's body when light comes from above.
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tysonfurybattlepass · 2 months
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im so close to doing this irl it’s unreal
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apostleoforder · 1 year
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hello c-side fans
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nettochu · 1 year
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Mighty Number Child
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swasdoodles · 3 months
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A Candor for the big OC collab on Derpibooru.
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