Humans are majorly daytime creatures with our senses optimized for day light such as sight for seeing light and to spot colors, and our other senses to compliment our sight helping us identify preys and finding food. When we go to bed at night, there is a whole world of living beings that come alive and are active at night. They are known as Nocturnal animals.
You might have noticed that your cats or dogs are very much active at night and can walk through your house without scattering things around, this is because they are nocturnal animals and there are few things that allows them to live and survive at night when we cannot.
These animals have gone through numerous evolutionary changes to get to where they are today, and these changes are visible in different parts of their bodies especially their sense organ. Unlike our eyes, nocturnal animals do not possess lots of cones which is important for color but they possess more rods for light and this is why their visions are usually black and white. They do not need lots of color to identify their prey, what they need is light to be able to see their environment and their preys.
Some nocturnal animals have vertical pupils which gives them control over how light enters into their retina. During they day, they have slit pupils but at night, their pupils expand to become a circle allowing over 100 times more light than when the pupils are undilated. Nocturnal animals have a layer of crystals at the back of their eyes which helps them bounce light to the retina and so increase their ability to see clearly. When you see animals that are night crawlers and night flyers, you would notice that they have a shining eyeball at night, this is thanks to the layer of crystals at their eyes.
They do not only depend on their sight, they also have better hearing and chemoreception to help them navigate and understand their environment. Mammals like bats have ears that are designed to hear extremely high pitch sounds which helps them to be able to identify when tiny insects passes. They can hear up to 120kHz which is very high and helps them with echolocation. Talking about chemoreception, insects that move at night rely on their antenna to get food and not their eyes. The chemoreceptors in their antenna help them search for certain chemicals such as carbon dioxide such as in the case of blood sucking insects, and other chemicals to find their prey.
Owls are another nocturnal animals that utilizes their ears properly. Owls have one ear sitting a little higher than the other and this allows them to be able to pinpoint the location of their prey in 3D. In other to catch their preys unaware, their feathers are also designed to make sure they are not heard when they take a flight so their prey do not know they are coming.
The vast majority of mammals are nocturnal animals such as canids, rodents, felines, marsupials, raccoons, tarsiers, and skunks, and there is a high chance we evolved from being nocturnal animals. Our nails being remnants of claws for digging, and so are many other parts of our body.
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