Biology

Crash courses and sparks for nature enthusiasts and explorers on various topics in biology and natural sciences with simplified lessons and insights.

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There is an international list of all threatened biological species that keeps track of their extinction risks. It is called The International Union for Conservation of Nature’s Red List of Threatened Species (IUCN Red List). Enthusiasts and organisations from many countries help by submiting and assessing the data. There is also another list called the IUCN Green List that keeps track of all the protected areas in the world.

Contrary to popular belief, polar bears don’t have white skin. Their skin is black underneath all that white fur, which is likely evolutionary to absorb more heat from the sun. You can see this around their nose or under the paws. But did you know that they aren’t always black? When they are born, they have a pinkish skin which only turns black after a few months.

Ever wondered how dolphins, whales, and seals sleep if they require frequent surfacing to breath? Dolphins are known to sleep and stay conscious simultaneously as they lack autonomic breathing. They sleep close to the surface of the water, either by maintaining a steady swim pattern or just floating.

And during their sleep, they keep one eye open. In other words, only one hemisphere is at deep sleep while the other in a state of wakefulness. This keeps them 🐬 aware of their surroundings, alerts the time to surface for air, and maintains other conscious functions. This is known as unihemispheric slow-wave sleep. Fascinating!

You all know what a circadian rhythm is! Biological functions like sleep and wake that are synchronised to the rotation of the earth over a period of approximately 24 hours. And you would also know that there are activities that cycle at a period longer than 24 hours — like menstruation in humans, migration and hibernation in animals. And of course, activities with shorter periods like hunger.

But do you know what these cycles are called? Just learned about the exact terms and they are super cool to say out loud!

Cycles that have a shorter period than the circadian rhythms are called ultradian rhythms. The ones that have a longer period, say like annually, are called infradian rhythms.