Today's Seal Is: Unlimited Scraggliness
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im sorry seals molt? my association with that word is insects so i am confused and intrigued
They do! I’d say most species of animals sloughs off “old” parts of their bodies at some point of their lives in some capacity. The word “molting” is used as a catch-all term for this process, although exactly what body part they shed and how they do it varies from animal to animal. Arthropods grow an entire new exoskeleton and shed the old one, but for most other animals, this process only involves shedding the outermost layer of their bodies, the pelage and/or their first layer of skin. Reptiles are quite famous for this because they sometimes manage to come out of their old skins and leave them almost fully intact as if they were kigurumi pajamas:
Mammals tend to mostly only shed fur or hair, growing thicker fur during colder months and losing it in favor of shorter fur during warmer months. How obvious this is depends on the climate, though. It’s quite perceptible in mammals that live in the arctic whose fur changes color depending on the season:
But even the difference between the summer coats and winter coats of domestic dogs can be palpable if you live in places with colder climates!
(I’m quite fascinated by this because I was born and raised in a tropical country and my dogs look the same all year round heh)
But back to the seals. Pinnipeds don’t really use their fur to keep warm like other mammals do, but they still have it, and they have to shed their old coats and grow new ones accordingly, which they do once a year!
In elephant seals, this process is so sudden and so extreme it’s called catastrophic molting. They don’t only lose their fur, but also a layer of dead skin all at once and this forces them to stay on land for a full month without swimming (and therefore, without hunting and eating) until the process is fully done. Because molting requires redirecting blood flow towards the skin instead of to their vital organs as usual, if they swam in the cold waters they’re usually accustomed to while molting, they’d freeze!
Bonus fun fact: despite having lost their fur during the evolution process, cetaceans like whales and dolphins also go through a molting process where they lose a layer of dead skin, which they scrape off by rubbing against rocks and rolling on sand banks.
It’s been recently discovered (as of 2020!) that the reason whales migrate annually from arctic waters to tropical waters is the exact same reason elephant seals spend a month on land: to molt! It’s much easier for a whale to keep warm while shedding its skin in warm waters than it is in cold waters.
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