What do you mean? An African or European swallow? I don't know!Well, there are 75 swallow species spread throughout the world. Of these species, about 37 reside in Africa, with only the West African swallow and the South African cliff swallow bearing the continent's name. On the other hand, the barn swallow is also referred to as the European swallow, so it's pretty clear where to look for data. So, which one are we going to use?Given that there have been significantly more studies on barn swallows, we're going to take a look at the European swallow. Wait, what is airspeed velocity anyway?It's “the relative velocity between some object,” or, for our purposes, between the swallow and the air. so, how do we find it?We use the Strouhal number, which can be calculated for birds as wingbeat frequency multiplied by stroke amplitude all over cruising speed. Stroke amplitude can be found using the formula bsin(theta/2), where b is wingspan, or the length of the wings, and theta is the stroke angle, or the angle between the highest and lowest wingtips. Cruising speed is the speed of the bird through the air, and therefore is the airspeed Velocity. So, to find the airspeed velocity of a barn swallow, we must know its Strouhal number, wingspan, stroke angle, and wingbeat frequency. in order to maintain airspeed velocity, a swallow needs to beat its wings 43 times every second, right?Wrong. In fact, according to a 2002 study done on barn swallows and house martins flying in free flight and wind tunnels “Compared with other species of similar size, the swallow has quite low wingbeat frequency and relatively long wings.” The results of the study found that the wingbeat frequencies of barn swallows range from 2.5 to 8.4 times every second, not 43. For a nice estimate, we can use the median numbers of 6.95 and 7.07 beats per second. What about the other variables?Well, the wingspans of the two aforementioned swallows are 0.318 meters for Swallow 1 and 0.328 meters for Swallow 2. At this point, as a non-professional, I turned to the work of someone who really knows what they’re talking about. Professor Graham Taylor of Oxford University found the stroke angles of the two birds to be about 95 and 90 degrees, respectively. This allows us to calculate a stroke amplitude of about 0.23 meters for both birds. The last number we need is the Strouhal number. Lucky for us, Taylor found Strouhal numbers of 0.18 and 0.19, respectively for the birds. All that is left to do is to find the average airspeed velocity by adding the two resulting cruising speeds (8.89 meters per second and 8.86 meter per second) and dividing them by two. So, what is the airspeed velocity of an unladen swallow?About 8.8 meters per second, or 20 miles per hour. Now, you may cross the Bridge of Death (and there was much rejoicing). curious? Here's some more info!
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Um, probably because your skin is being ripped open. yes, but why Are they so much more painful than a normal cut or scrape?Because paper cuts usually occur on fingers, which have a lot of pain receptors. This makes getting a cut on your finger the equivalent of getting one on your face. So, why do we have so many pain receptors on out fingers?It’s one way we protect ourselves. Think about it: our fingers are used to do pretty much everything, from opening doors to typing. It makes sense that they should be sensitive to anything hot or sharp. But paper isn't sharp.Wrong. One quick glance at a piece of paper magnified at 100x shows that the edge of a piece of paper isn’t as smooth as it appears. But that’s only half the problem. See, a knife, while sharper than a piece of paper, is straight and sturdy and therefore only performs one, quick slice. The flimsyness of paper means it doesn’t perform a clean cut, but rather flexes a little, causing microscopic damage to the skin. ThEn why don't paper cuts bleed evEry time? Because, as I stated earlier, our fingers are full of pain receptors, and paper isn’t as sharp as a knife. How do those relate to anything?Patience, grasshopper. I’m getting there. Let’s start with the dullness of paper. Paper is just not sharp enough to draw blood. It cannot go that deep into the skin. This means that the normal blood clotting and scabbing that helps close and protect wounds doesn’t occur. Furthermore, on the second point, this leaves your pain receptors exposed to the outside world so, unless you quickly cover them, it will be painful. is there ANYTHING i can do to make it less painful?Unfortunately, scientists can’t exactly conduct studies on paper cuts as no one willingly wants to subject themselves to such pain. However, the best solution is to immediately seal the cuts as best you can, be it with a bandage, Vasaline, or even Super Glue. This will prevent the pain receptors from being exposed. So, why do paper cuts hurt so much?Paper cuts hurt because our fingers are sensitive to pain, paper is both rough and flexible, and paper cuts are shallow enough to leave pain receptors susceptible to the outside world. curious? Here's some more information!
A caterpillar turns into a butterfly. Yeah, but how?Well, are you asking about a chrysalis or a cocoon? is thEre a Difference?Of course there is! The three words used to describe where metamorphosis takes place are pupa, chrysalis, and cocoon. A pupa is used to refer to the naked stage of either butterflies or moths. A chrysalis is the same thing, but only for butterflies. A cocoon, however, is the silk a moth larvae spins around itself before it becomes a pupa. Ok, then let's just talk about pupas. How do LARVAE know when to start Making them?As those of you who have ever read The Very Hungry Caterpillar know, larvae essentially eat until they can’t anymore, at which point they are full grown, molting many times in the process. but how can you tell? Is it just random?Very few things in nature are random, dear reader. There are some things to look for in a larvae to figure out if it’s about to make its pupa. One is that it stops eating, you know, since it pretty much has been eating constantly. Related to that, it might start regurgitating undigested food (hey, you asked). Some larvae will move off the plant to find a safer place to build a pupa since, it obviously won’t be eating from that plant anytime soon. Changes in coloring can also signify the larvae is ready to pupate. wait, how does it build a pupa?Well, first it wanders around aimlessly for a day to find the perfect spot. After this, the process varies form species to species. Some attach their tails to the plant using silk, while others attach both their tails and their waist. Larvae without this ability often pupate on the ground. Some hang off high branches, while others go close to the ground. Regardless, they curl themselves up and spend around two days preparing for its last molting. However, instead of shedding skin and walking out, it sheds its skin to reveal a soft, seemingly lifeless pupa. what about the ones that cocoon?For cocooning larvae, it is essentially the same, but the molting takes place within the silk cocoon. (Side note: cocoons are actually really cool. My personal favorite is the urodid.) so, what happens inside the Pupa? Do they turn to mush?No. Larvae do not turn to mush inside the pupa; this is merely a common misconception (thanks, Tumblr) disproved by a 2013 study of larvae using CT imaging. While some parts of the larvae disintegrate, the lungs, guts, brain, and other organs essentially remain the same. Additionally, many butterfly/moth parts already exist inside the larvae, called imaginal discs, and undergo rapid development rather than dissolving, such as legs, antennae, eyes, parts of the mouth, genetalia, and the wings. do you mean to tell me that caterpillars have wings?Not necessarily. The imaginal discs that eventually become wings are, for the most part, just “blobs of tissue” that later develop into things such as wings. how does the rest of the body develop?Well, here’s the thing. When you already have all of your internal organs, there’s not much left to do. The outer cells of the larvae-soon-to-be-winged-creature reform to make a body, and the wing scales grow and change color. Other than that, it’s pretty much just a lot of growth. However, it is a lot of growth, which is why metamorphosis takes an average of two weeks (24 days). So, what happens inside a chRysalis?A caterpillar dissolves minus its internal organs and imaginal discs, which undergo rapid growth while the body is reformed around them, eventually creating a butterfly. CURIOUS? HerE's some more reading!
Well, they have brains that control all of their bodily functions, just like us humans. I mEan, how do they camOuflage themselves?Actually, the purpose of changing skin color isn’t to camouflage; the skin cells respond to the chameleon's emotions. (Basically, their entire skin is a mood ring.) The skin also changes color in order to regulate the chameleon's body temperature and attract potential mates. Fine, then how do they change their skin color?They have a special layer of skin cells, called nanocrystals, that are adjusted to reflect different frequencies of sunlight. how does that work?Well, I’m glad you asked. So, chameleons have two layers of skin. The top layer contains two layers of nanocrystals, “iridescent cells that have pigment and reflect light”. When a chameleon is relaxed these nanocrystals reflect shorter wavelengths of light, like blue and green. However, when the chameleon is excited, the nanocrystals spread out, reflecting long wavelengths, such as red and orange. Then why aren't Chameleons blue all the time?Well, underneath all of these nanocrystals is a layer of yellow pigment, which mixes with the blue reflected light to create a green. This yellow pigment lies below the nanocrystals, as yellow as a color is particularly susceptible to UV rays. Also, only males are equipped with these nanocrystals. While females and juveniles have some color-changing capabilities, they pretty much remain brown, which is also a sort of camouflage when you think about it. SO IT THAT HOW OCTOPUSES And such work, too?Not really. Octopuses are among a number of cephalopods that can change their color instantly, including squids and cuttlefish. They use chromatophores, which are cells that contain what is essentially microscopic sacks of paint. Additionally, while chameleons' color changes are activated by heart rate and motion, octopuses' are controlled by “a complex array of nerves and muscles”. This allows octopuses to regulate their appearances more easily. As a result, not only can octopuses change their skin into different colors and patterns, but they can also change its texture, which a chameleon definitely can’t do. SHOULDN'T IT BE “octopi”?Nope. Only words with Latin roots end with an “i”. Therefore, since the word “octopus” has a Greek root, the correct term is “octopuses”. People just changed it to sound fancy (also, it’s fun to say), and now it’s considered correct by spell-check, when it’s technically not a real word. WHATEVER. Can we get back to chameLeons?Please. how do they do that eye thing?Now this is a different story. Their eyes rest not the sides of their head in cones, not sockets, allowing for free movement. To keep the eyes from falling out, chameleons have developed a muscular eyelid that protects it from dangers, as it is so exposed, and makes sure the eye itself doesn’t roll away. This gives the chameleon the ability to have practically a 360 degree view of its surroundings. What about when the eyes move in DIFFERENT directions?Two separate groups of nerves work the eyes, allowing them to move independently. This ability gives the chameleon a panoramic view while searching for prey. Once the prey is located, the chameleon will once again use its eyes together. It also gives chameleons crazy good reflexes, as they can see everything all the time. so, how do CHAMELEONS work?Chameleons change color involuntarily by raising their heart rate and feeling emotions, which changes the spacing of the nanocrystals in their skin (totally different from octopuses), and move their eyes in strange ways through the use of cone-like eye sockets and separate nerve bundles for each eye. curious? Here's some more reading!
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