1

Money Materials

Image: Jorge Salvador

We call them paper bills, but do they undergo the same process as any other paper? Naturally, they don’t. U.S. bills are mainly made of two materials: 75% of their composition is cotton and the 25% left is linen. Besides, they have randomly disbursed red and blue security fibers embedded in the paper.

This special blend is made by only one company in America and that is Crane & Co . The company, based in Massachusetts patented this special blend and it has been the sole provider of paper for currency since 1879.

2

Origin of the U.S. dollar symbol

Image: Paris Bilal

The dollar sign is a matter of debate. One line or two across a capital S, the symbol is today a worldwide sign for money, but where does it come from?

Even if there are several theories as to where the U.S. dollar symbol comes from, all of them agree that it was derived from the Spanish peso . When the time came, and the new nation needed its own currency, the basis was that of the Spanish coinage, which was the most common currency in the colonies before the country’s independence.

The adoption of the sign was made official in 1785, and today, the United States is not the only country that uses this symbol, Canada, Australia, and New Zealand do too!

3

Who appears on the bills?

Image: AR

Having your face forever stamped on the little piece of paper that rules the world should be a milestone in your career, right? However, there were certain rules as to who qualifies to be granted this honor .

Probably, the most surprising, yet the most logical one is that no living person can be portrayed in American currency. Since the Founding Fathers considered it unpatriotic to be portrayed while alive, this was first a tradition and then made official in an Act of Congress in 1866 .

However, contrary to popular belief, this honor is not only reserved for presidents! Anyone who contributes to the nation can be portrayed.

4

Folding Papers

Image: Emilio Takas

Bills come and go all the time. We take them out of our pockets and put them in our purses only to take them out again a few hours later and give them to the shop assistant. For a life that busy, we can only hope the paper is tough enough , right?

Well, as a matter of fact, it is. Compared to regular paper, which can only be folded 400 times before it breaks, money paper can be folded up to 8,000 times before it breaks .

It's not that you’re going to try it out and see, but you can rest assured: Fold your bills away, they can handle it!

5

Damaged Goods

Image: Jp Valery

Even if they can be folded that many times, the life of bills is limited, not to mention accidents happen. Who hasn’t sent a bill to the washing machine by chance?

So, what happens when a bill is damaged? Well, at least 50% of it has to be clearly identifiable for the bank to replace it , otherwise, you’ll just lose your money. You don’t feel like folding them much now, right?

On the other hand, and mainly due to time damage, at least 70% of the new bills are used to replace old bills . These bills, once taken out of circulation are shredded and sent to companies that can recycle them!

6

Security Features

Image: Colin Watts

Counterfeiting has been a problem ever since paper money was created and statistics about which countries counterfeited most of the money are simply shocking. But we won’t get into that.

What we will say is that thanks to technological advancement, the U.S. bill is getting harder and harder to counterfeit. In modern bills, there are at least six security features which are: UV security ribbon, raised printing, microprinting, 3D security ribbon, color-shifting ink, and traditional watermarks. Do you pay attention to them?

7

U.S. Coins

Image: Kenny Eliason

Coin production in America is in charge of the U.S. Mint and there are four production facilities across the country. They are located in Philadelphia, Denver, San Francisco, and West Point.

It is estimated that every year the Mint produces about 16 trillion coins which are valued at over $1.09 billion dollars. What is truly impressive is that Americans throw away an estimated 62 million dollars worth of coins every day!

They may not be worth much alone but don’t throw them away, all of them together can make you rich!

8

Green Ink

Image: maria pagan

Have you ever wondered why the U.S. dollar bills were green? It is not about design or aesthetics, even if we think they look pretty.

The decision to use green ink was a matter of security, in order to prevent counterfeiting. Back then, black and white ink made it easier to create photographic fakes. For that reason, green was the color of choice, and, when paper money was standardized in 1929, it had great acceptance due to the positive connotations of the color . Do you like it?

9

Andrew Jackson’s Take on Paper Money

Image: Elsa Olofsson

Every denomination has an important figure stamped on the front. In the case of the 20-dollar bill, Andrew Jackson was the chosen one.

Jackson was the seventh president of the United States and, even if it is not a rule that only presidents can be portrayed, his contributions gained him this honor.

Ironically, Jackson was not in favor of using paper money. For him, only gold and silver coins should have remained legal tender. After learning this, one can only assume he wouldn’t be so happy to be the face of the 20-dollar bill, right?

10

Facelifts and redesigns

Image: Kenny Eliason

One of the ways of keeping paper money safe and hard to counterfeit is by giving the bills new designs.

New faces were expected to appear in future bills, but, in the meantime, the changes always had to do with the proportions of the elements within each denomination. Bigger faces, rearrangement of the signatures, stuff like that.

Now, these changes and facelifts haven’t reached all the bills. 1-dollar bills haven’t been changed or redesigned ever since 1929. Why is that? Because it is not worth the trouble for criminals to counterfeit. One dollar won’t take them too far!

1

Woodpecker

Image: Jaime Dantas

Surely, we could all recognize Woody Woodpecker's famous laugh anywhere, but have you ever wondered why this type of bird knocks on wood? Woodpeckers have larger and stronger bills than other birds. They use their beaks not only to dig holes in trees for nesting but also to drum on resonant objects like hollow logs and branches to communicate to other woodpeckers, about their territory and their availability to mate.

But is it true that they hammer away at wood at an incredible speed, as seen in the beloved cartoon? Yes! For example, the Red-headed Woodpecker, found in temperate North America, has the highest g-force (force of acceleration) experienced by a bird. When pecking wood, they hit trees with an impact force of 1,200 g’s. By comparison, astronauts on space shuttles experience 3.5 g's during takeoff, while a force of 60-100 g’s can cause a human concussion.

2

Northern Cardinal

Image: Joshua J. Cotten

Did you know most female songbirds in North America usually don't sing? Fortunately, both male and female Northern Cardinals break this trend with their beautiful songs . As a matter of fact, sometimes they even perform duets! Mated pairs usually sing back and forth to each other, sharing information about food sources and nest activity.

Another cool fact about Northern Cardinals is their tendency to fight their own reflections in windows and vehicle mirrors. Experts claim they see their image as a competing bird and attack it to defend their territory. This behavior can go on for days, even months.

Nevertheless, despite this somewhat aggressive attitude, Northern Cardinals are one of America's favorite birds. They hold the distinction of being the state bird of seven states: Illinois, Indiana, Kentucky, North Carolina, Ohio, Virginia, and West Virginia.

3

Brown Thrasher

Image: Joshua J. Cotten

The Brown Thrasher may be an elusive, hard-to-see bird but it certainly doesn't go unnoticed. The state bird of Georgia, found throughout the eastern and central United States and southern and central Canada, is well known for its remarkable songs.

In fact, this big, foxy-red bird is not only a prolific singer but also an expert mimic, with an impressive repertoire of more than 1,100 tunes! And thrashers are so good at keeping the natural world entertained that they will repeat each phrase of a song twice before singing the next one.

4

Northern Mockingbird

Image: Patrice Bouchard

The Northern Mockingbird is another remarkable mimic. This bird listens to the songs of nearby species and learns to replicate their tunes. In fact, a male may learn around 200 songs throughout its life. The mockingbird, however, can be a bit more monotonous than the Brown Thrasher: it repeats phrases up to six times before moving on to the next one. Have you ever had one in your backyard?

Apart from its musical abilities, the Northern Mockingbird, very common in towns and cities, especially in the South, is one of the most influential birds in American culture. It serves as the state bird for five states : Arkansas, Florida, Mississippi, Tennessee, and Texas. It also appears in many books, TV shows, folk songs, and lullabies.

5

Marsh Wren

Image: Alexis LOURS

Marsh Wrens are songbirds too, but in their case, it’s all about impressing the ladies! The Marsh Wren, a tiny brown bird found all around North America, learns songs from other males and sings them nearly identically. With a repertoire of more than 100 melodies, males often engage in musical duels and sing back and forth to each other to impress the females with their musical abilities.

But singing isn’t their only strategy for winning over a mate. Male Marsh Wrens build up to 20 dummy nests made from cattails for prospective females to evaluate. The female then chooses which one she prefers to lay her eggs in. Unused nests are left as is to confuse predators or are used by adult birds to sleep during nonmating seasons.

6

Black-capped Chickadee

Image: Margaret Strickland

The Black-capped Chickadee, the state bird of both Massachusetts and Maine, is a very popular bird across the northern United States. This small black, white, and tan bird, roughly the size of a sparrow, is well known for its vocalizations and for its ability to conserve energy during the winter months.

In extremely cold weather, Black-capped Chickadees enter a state of dormancy known as torpor. At night, the birds seek shelter and become inactive, causing their core body temperature to drop slightly. As they alternate shivering with staying still, the heart rate decreases. When they reach a full state of torpor, they lose consciousness. Toward morning, the birds start shivering again to regain temperature. This way, the Black-capped Chickadee starts the day afresh, using the precious fat it saved during the night as energy.

7

Ruby-throated Hummingbird

Image: Skyler Ewing

They might be tiny but the myth that Ruby-throated Hummingbirds migrate on the backs of Canada Geese is totally false. Ruby-throated Hummingbirds, the most common hummingbirds in eastern North America, migrate south at the end of summer, traveling to temperate climates in Central and South America entirely on their own.

This iridescent red and green bird is so small that it makes the most minuscule nests. The nest of a Ruby-throated Hummingbird is around the size of half of a walnut shell—only 1½ inches wide! Also, the smaller the bird, the fewer the feathers. The Ruby-throated Hummingbird is a record holder for the fewest feathers in a bird, less than 1,000 in total. For reference, a Whistling Swan, the record holder for the most feathers, boasts about 20,000 individual feathers.

8

Owls

Image: Keith Lazarus

Owls are both cherished and mysterious creatures. In North America, there are 19 different species, each with its own curious characteristics. For example, the Elf Owl, found in the Southwestern United States and Mexico, is special because it’s the smallest owl in the world —measuring just 5 inches tall!

Night-hunting owls present in North America, such as Barn Owls, Long-eared Owls, and Boreal Owls, have the best hearing in the bird world. Many of these nocturnal owls have asymmetrical ear openings, one opening higher and one larger. This unique adaptation allows sound to enter their ears at slightly different times, helping them to accurately triangulate the position of their prey. Also, Barn Owls have a specialized middle claw called pectinate claws. This special feature is a serrated edge that serves as a built-in comb to get rid of debris or parasites.

9

Snow Goose

Image: David Dibert

Isn't it great when we get to spot those amazing V-shaped migration formations in the sky? Did you know that most of North America’s small birds don’t fly in formations? They travel alone or alongside other birds that happen to be heading in the same direction. The Snow Goose, however, is an exception, often flying in huge V formations or single-angled lines.

During migration, Snow Geese, native to North America, form some of the largest flocks in the bird world. Flocks of more than 100,000 Snow Geese are a common sight during their northward spring migration. In some areas, such as Nebraska, there are even records of flocks with millions of geese. Flying in formations allows Snow Geese to save energy during flight.

10

Bald Eagle

Image: Pixabay

If you thought that, since it’s the national symbol of the United States of America, you knew all about the Bald Eagle, these facts will probably blow your mind! Did you know that young Bald Eagles are born with brown eyes, which eventually turn yellow? And what about the fact that they have talons that can grow up to 2 inches long , helping them grasp prey tightly for a quick kill?

Furthermore, Bald Eagles make the largest nests of any bird species. The largest Bald Eagle nest ever recorded measured more than 9 feet wide and 20 feet deep and was found in St. Petersburg, Florida. What's even more impressive is that they reuse their nests for many years—sometimes even decades. A Bald Eagle nest in Vermilion, Ohio, was used for 35 years in a row—mortgage-free! Can you imagine?

1

Beehives

Image: Meggyn Pomerleau

The first entry on the list goes to perhaps the most famous and finest example of animal architecture: the beehive. Built by incredibly industrious insects, beehives are among the most efficient structures in nature .

The regular hexagons provide the least-perimeter way to enclose infinitely many unit areas in the plane: the best way to separate the surface of their hives in equal parts all around, using the least possible total perimeter, thus reaching 100% efficiency in design.

2

Ant colony

Image: Morten Jakob Pedersen

If beehives aren’t the first thing that comes to mind when thinking about animal architecture, there’s a good chance you’re thinking of ant colonies.

Ants build the elaborate colony structure by hollowing out the area with their mandibles, grain by grain, without a blueprint, without a leader, and in total darkness . Unless the soil dries out dramatically, the chambers will keep their form.

3

Prairie dog town

Image: Moritz Kindler

These cute creatures excavate their homes by digging burrows into the ground, primarily in the Great Plains of North America. The region experiences extreme seasonal weather variations from season to season, requiring their homes to be built to withstand extreme temperatures, floods, and fires.

These underground "towns" have nursery rooms, pantries, living quarters, and temporary refuges —each smartly separated to serve a specific purpose.

4

Beaver dam

Image: Derek Otway

Another famous animal architect, the beaver, uses felled trees to build dams . These dams create still ponds where beavers can construct their winter homes, called lodges.

These creatures prepare for winter by covering their lodge with a fresh coat of mud, which hardens to create a barrier against the cold and predators.

5

Caddisfly larvae case

Image: Wolfgang Hasselmann

Caddisfly larvae construct protective cases using silk and whatever materials are available , such as sand, small stones, and plant debris.

These cases camouflage the larvae from predators and can be remarkably diverse in appearance, reflecting their creativity and resourcefulness.

6

Octopus den

Image: Serena Repice Lentini

It’s no secret that octopuses are incredibly intelligent animals, and their dens are proof of it. These clever mollusks use shells, stones, and even discarded human objects to reinforce their homes . Some species go a step further, decorating their dens with seaweed and other found materials.

7

Bagworm silk tent

Image: Maëva Vigier

Bagworms construct silk tents around themselves using bits of leaves, twigs, and other debris . These tents serve as mobile homes, providing protection as the insect feeds and grows.

Some species even camouflage their bags to blend into the environment, helping them avoid predators.

8

Osprey nest

Image: Jorge Coromina

Ospreys build massive nests in tall trees or on human-made structures near bodies of water. These nests are carefully constructed with sticks and lined with softer materials , creating a sturdy platform that can last for multiple breeding seasons.

9

Coral reef

Image: Hiroko Yoshii

Coral reefs are massive structures built by tiny coral polyps. These marine architects secrete calcium carbonate to form hard skeletons, gradually creating vast and complex habitats for a myriad of marine species. They are often referred to as the "rainforests of the sea" due to their biodiversity.

10

Spider web

Image: freestocks

Another famous architect from the animal kingdom, the spider, creates webs that serve as both homes and hunting tools . The silk used in these webs is incredibly strong, and different species produce a variety of designs, including sheets, orbs, and funnel shapes.

11

Swallow nest

Image: Tobias Arweiler

Swallows build cup-shaped nests that can house entire colonies , using mud pellets, usually attached to vertical surfaces like cliffs or man-made structures.

The construction is precise and stable, providing protection for their young against predators and environmental elements.

12

Burrowing owl burrow

Image: mana5280

As their name suggests, burrowing owls make their homes underground , often taking over burrows abandoned by prairie dogs or other mammals.

They use these subterranean homes to protect their young and hide from the heat of the day.