June 28, 2023
At this time, the days are at their longest and most people feel fine with that. We are, in fact, true ‘day creatures’, conditioned to live in broad daylight and distraught when plunged into darkness. However, some animals are used to the dark and only show their best side once the sun has set. How did they adapt to these circumstances? What superpowers have they developed?
Have you ever had the eyes have you ever studied an owl up close? They represent as much as 5% of their total body weight, which is gigantic compared to our own eyes. Because when it comes to looking in the dark, the size matters: the larger the eyeballs and the larger the pupils, the better the animals can absorb the light. In addition, they have one reflective layer on the back of the retina, the tapetum lucidum – Latin for ‘luminous carpet’ – which reflects light and makes their eyes glow at night. But besides its eye-catching effect, this reflective layer also makes it possible to capture more light at low brightness.
Rollin Verlinde
Another difference: the eyes of nocturnal animals contain many more rods – light-sensitive cells that facilitate vision in the dark, but do not pick up colors. Most vertebrates have only one type of rod, so we can only distinguish shades of gray and black at night.
Fish from the deep sea have pushed that evolution even further: they have different types of rods developed, which gives them a more nuanced view. The university of queensland (Australia) has discovered in thirteen fish species that they have genes capable of different forms of rhodopsin, a light-sensitive protein, to encode. And unlike the rods of other vertebrates, which only see black and white, their rhodopsin would also allow them to perceive different shades of blue.
Bioluminescentie
Other animals do not have this exceptional vision, but have found another trick: if there is no light, they create it themselves. Basically, they cause a chemical reaction and convert that energy into light. For example, this technique is used by fireflies when they are looking for a partner, but also by the dwarf squid to evade predator attacks. Bioluminescence in nocturnal or abyssal species (with the deep sea as habitat). often have a function other than simply helping them to see better: It is used to attract mates, deter predators or communicate.
Rollin Verlinde
Very sharp hearing
Owls not only have excellent eyesight, they can also hear the slightest sound. Why? Thanks to them asymmetrical ears! Because their ear canals are at different heights, sounds do not arrive at the same time in both ears and so they can pick up different types of information. Other animals, such as cats, can easily move their ears back and forth and point them in the direction where the sounds are coming from to better identify them. And here again, size matters: long-eared bats can perceive even the smallest moving insect, because the sound is amplified by their gigantic floppy ears.
Echolocation
You can also easily find your way through the dark night via echolocation, a well-known technique that bats have mastered. For a bat it is enough to have one ultrasonic sound to produce, then that bounces off surrounding objects, to get all sorts of information: the distance between walls or objects, the presence of obstacles or prey… All this information is processed in a few seconds by the parietal lobe in the brain. Very handy if you want to hunt (almost) blind! Certain cetaceans and even the shrew also use this technique, which has long proven its worth.
Rollin Verlinde
Smell and touch organs
And what role does the sense of smell play in all this? Mammals and reptiles have an organ called the vomeronasal organ – also known as the organ of Jacobson – is called. It is located at the level of the palate, through which also pheromones can be observed. In order for this organ to work, some animals roll up their lips when they sense an odor.
Also nerve endings play a role in animals that have to find their way in the dark. For example, moles have Eimer’s organ, a very sensitive organ of touch, on their snouts.
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2023-06-28 07:01:22
#animals #adapt #night
