Horseshoe Crabs

In observance of beach season, today’s post honors one of the sea shore’s oldest inhabitants: the horseshoe crab.

Horseshoe crabs date back to the Ordovician Period, and haven’t really changed in the intervening 450 million years; these ancient origins have earned them living fossil status. With their hard, dome-shaped shells, horseshoe crabs look like fossils; they molt this armor about 18 times over their life to keep growing. Under the shell, they have five pairs of clawed legs that converge at a central mouth. Instead of teeth, their mouths sport stiff bristles for eating mussels and worms.

Men's Hats

Do you long for an age when women were women and men wore hats? Today, learnalittle has you covered… well, learnalittle has that second part covered.

The fedora reigns king of the felt hats. Fedoras have a brim that goes all the way around the crown (or top), and traditionally sport a grosgrain ribbon hat band (a silky, ribbed material). The crown can be bashed or blocked – indented and/or creased – in various styles, but the most common is a crease down the center with a pinch on both front sides. Recently popular Trilby hats are very similar to fedoras with some notable differences: a shorter crown and narrower brim that turns up in the back.

Botox

Sterilize the area for an injection of knowledge: today’s learnalittle topic is Botox.

Botox is a form of botulinum toxin (pronounced “botch-uh-line-um”), a protein produced by the bacterium Clostridium botulinum. If ingested, the toxin causes botulism (“botch-uh-liz-um”), a potentially fatal paralytic illness. C. botulinum thrives in neutral pH, low-oxygen environments, and is sometimes found in tainted canned foods. The first recorded case of botulism occurred in 1735 Europe, presumably caused by poorly prepared sausage (“botulism” actually comes from the Latin for sausage, botulus).

Amazons

It’s ladies’ choice today on learnalittle, as we explore the timeless tale of the Amazon warrior women.

The Amazons were a tribe of female warriors living in the Greek Classical period (5^th and 4^th centuries BCE). Ancient historians and artwork portray Amazons as expert with all weapons, battling Greek men with considerable skill. Some legends report Amazons as the first to ride horses, though the practice more likely originated thousands of years earlier.

Dark Matter and Dark Energy

Space. As far as frontiers go, it’s pretty final – and even more mysterious. In this spirit, today’s post covers two of astrophysics’ most brain-boggling theories: dark matter and dark energy.

Our first mystery arose in 1933, when Swiss-born astrophysicist Fritz Zwicky attempted to estimate the total mass of a cluster of galaxies. But he encountered a problem. As background, the more mass an object has, the greater it’s gravitational pull – the force that attracts other objects. The greater an object’s gravitational pull, the faster objects rotating around it will move. Zwicky noticed that galaxies at the edge of the cluster were rotating way too fast for the mass he calculated; to account for speed, the cluster had to be about 400 times more massive.

Conception

Brace yourself: it’s time for The Talk. Today on learnalittle, clear up those misconceptions about conception.

Natural conception (or fertilization) requires sexual intercourse between a male and female. Healthy men typically release around 300 million sperm into the vagina during ejaculation.  Sperm are the male gamete (reproductive cell) and have pinched, oval-shaped heads. A sperm swims using a flagellum tail that continuously whips back and forth. Despite this ideal structure, about 60% of sperm are imperfect even in the healthiest men. Many have multiple tails, are unable to move, or are otherwise defective. These sperm never escape the vagina, destroyed by its acidic 4.5 pH within hours. Their more successful siblings head toward the cervix.

Rainbows

Ditch the rose-colored glasses and prepare yourself for full-on Technicolor. Today on learnalittle, we’re chasing rainbows.

Rainbows appear when sunlight passes through moisture droplets in the atmosphere, producing a colorful ring – though only an arc is visible. When the sun is about 42° above the horizon (in the early morning or evening), droplets of moisture behave much like prisms: a ray of light refracts as it enters the droplet, reflects off the back, then refracts once more as it passes out of the droplet. This process disperses the ray into the colors of the visible spectrum of light.

Hinduism

Unfurl your yoga mats and focus on your computer screen. Today on learnalittle, it’s a brief look at Hinduism.

Hinduism is perhaps the oldest surviving religious tradition, dating back to 1700BCE or earlier and evolving from thousands of years of separate practices from the Indian subcontinent. Because it lacks a historic founder and a single concept of god, Hinduism isn’t one “religion,” but an incredibly varied collective of traditions and beliefs.

Colons

Lace up your grammar gloves, step into the ring, and brace yourself for Punctuation, Round II. With the fearsome semicolon now a familiar friend, we move on to the slightly better understood (but still somewhat confusing) colon.

Colons have several uses, but all of them follow a basic rule: a colon follows an independent clause (or a full, stand-alone sentence) to provide an example or additional, needed information. Consider that last sentence. In the initial independent clause, I said there was a “basic rule”; after the colon, I explained what that basic rule was.

Neurotransmitters

Learning, emotions, sensation, sleep – believe it or not, we owe all of these processes to microscopic chemical signals called neurotransmitters.

Before tackling the main neurotransmitters and their functions, let’s review how neurons – the specialized cells of the nervous systems – work. Neurons are electrically excitable, and relay information by changing their concentrations of charged ions in a process called action potential. An action potential will eventually travel down the axon, a tube-like projection that links neurons to other cells and each other at a synapse. At the end of the axon, neurotransmitters are released into a space between the excited neuron and another neuron or cell. By binding to specific receptors, neurotransmitters can excite, inhibit, or otherwise change a cell; in turn, these cellular changes can have some big affects on the whole organism.

Naked Mole Rats

They say to not judge a book by its cover, but they might need a more convincing adage to keep us from judging the naked mole rat. Though a little hard to look at, these rodents have a lot more going for them than their horror movie-worthy appearance.

Naked mole rats are native to East Africa, living in elaborate underground burrows and tunnels that they dig with their large teeth (their lips are behind these teeth to prevent dirt from getting in their mouths). Their small bodies – 3 to 4 inches long and 30-35 grams – and short legs are ideal for navigating cramped tunnels; they can scurry quickly both backward and forward.

Mole rats rarely leave their burrows: their mostly hairless, almost pigment-less bodies don’t fair well in the sun and their weak, beady eyes give them poor visual acuity. Fittingly, mole rats live mainly on tubers – starch-rich vegetables that grow underground. Additionally, mole rats have naturally low metabolisms and eat relatively infrequently; they can reduce their metabolisms even further when food is scarce.

Seven Wonders of the World

Historically, humans are inclined to compete, astonish, and outdo. Truthfully, these sometimes-childish tendencies have led to some pretty impressive things. Today, we’ll explore some of the oldest and grandest examples: the Seven Wonders of the World.

The Colossus of Rhodes is perhaps the youngest of the seven, built around 290BCE in Rhodes, Greece. At over 100ft tall, the statue resembled a considerably more naked Statue of Liberty.  Though shaped like the immortal Titan-god Helios, the Colossus stood only about 56 years and fell in a 226BC earthquake.

Jellyfish

There are some creatures that seem too strange to be true. Chief among them are the ghostly, alien – and sometimes deadly – jellyfish.

“Jellyfish,” although widely used, is considered a misleading name, as they aren’t related to fish. Instead, researchers prefer the terms jellies and medusas. Medusas belong to the phylum Cnidaria (pronounced “nidaria”) along with corals, anemones, and certain parasites. The incredibly venomous Portuguese Man o’ War is also among this group, but – despite a striking resemblance – it’s a siphonophore, not a medusa.