What Causes Eye Floaters?

iStock / Mark_Kuiken
iStock / Mark_Kuiken

Eye floaters — or muscae volitantes, Latin for “hovering flies" — are those tiny, oddly shaped objects that sometimes appear in your vision, most often when you’re looking at the sky on a sunny day. They look like spots, or a squishy little amoeba, and drift aimlessly around in your field of vision. Try to get a fix on one, though, and it seems to disappear.

Floaters aren’t just optical illusions. You’re really seeing them, and they’re actually in your eye, not just on it or in front of it. The weird little squiggles are pieces of the vitreous humor, the fluid that fills the eye, breaking off and then floating about in your eyeball.

A little gross, I know, but completely normal. The vitreous humor fills the gap between your retina and lens and helps maintain the round shape of your eye. It’s made up of water bound up in a little hyaluronic acid and collagen. When you’re young, it’s thick and gel-like, but as you age, the hyaluronic acid network breaks down and releases the trapped water molecules. As this happens, the core of the vitreous humor becomes more watery and little bits of undissolved gel break off and slowly drift around. When light passes through the eye, the shadows of these pieces are thrown up on your retina and you perceive them as floaters.

A Closer Look

Since floaters, well, float, their paths generally follow the motion of the eye. This makes looking right at them difficult, and when you shift your gaze towards them, they often move and stay at the edges. They don’t always float, though, and many of them will sink towards the bottom of the eyeball. To get a good look at them, just lie down looking up at a clear sky. Some of the floaters will settle near the fovea, a small area that sits at the back center of your eye and is responsible for your sharp central vision. The lack of movement and the even, textureless background makes it easy to scope them out and watch the blobs bob around a little.

For the most part, floaters are nothing to worry about — just a sign that you’re not a kid anymore. The sudden appearance of a lot of floaters combined with the onset of other eye weirdness — like flashes of light or blurriness or loss of peripheral vision — could indicate a problem, though. Sometimes, floaters are a symptom of the vitreous humor pulling away from the retina, a retinal tear, or the abnormal growth of blood vessels in the eye. If your floaters cross the line from curiosity to nuisance, it’s time to give the eye doctor a call.

What's the Difference Between a Rabbit and a Hare?

iStock.com/Carmen Romero
iStock.com/Carmen Romero

Hippity, hoppity, Easter's on its way—and so is the eponymous Easter bunny. But aside from being a magical, candy-carrying creature, what exactly is Peter Cottontail: bunny, rabbit, or hare? Or are they all just synonyms for the same adorable animal?

In case you've been getting your fluffy, long-eared mammals mixed up, we've traveled down the rabbit hole to set the record straight. Although rabbits and hares belong to the same grass-munching family—called Leporidae—they're entirely different species with unique characteristics. It would be like comparing sheep and goats, geneticist Steven Lukefahr of Texas A&M University told National Geographic.

If you aren't sure which animal has been hopping around and helping themselves to the goodies in your vegetable garden, take a closer look at their ears. In general, hares have longer ears and larger bodies than rabbits. Rabbits also tend to be more social creatures, while hares prefer to keep to themselves.

As for the baby animals, they go by different names as well. Baby hares are called leverets, while newborn rabbits are called kittens or kits. So where exactly do bunnies fit into this narrative? Originally, the word bunny was used as a term of endearment for a young girl, but its meaning has evolved over time. Bunny is now a cutesy, childlike way to refer to both rabbits and hares—although it's more commonly associated with rabbits these days. With that said, the Easter bunny is usually depicted as a rabbit, but the tradition is thought to have originated with German immigrants who brought their legend of an egg-laying hare called "Osterhase" to America.

In other ambiguous animal news, the case of Bugs Bunny is a little more complicated. According to scientist and YouTuber Nick Uhas, the character's long ears, fast speed, and solitary nature seem to suggest he's a hare. However, in the cartoon, Bugs is shown burrowing underground, which doesn't jive with the fact that hares—unlike most rabbits—live aboveground. "We can draw the conclusion that Bugs may be a rabbit with hare-like behavior or a hare with rabbit nesting habits," Uhas says.

The conversation gets even more confusing when you throw jackrabbits into the mix, which aren't actually rabbits at all. Jackrabbits are various species of large hare that are native to western North America; the name itself is a shortened version of "jackass rabbit," which refers to the fact that the animal's ears look a little like a donkey's.

A jackrabbit
Connor Mah, Flickr // CC BY-SA 2.0

As Mark Twain once famously wrote about the creature, "He is just like any other rabbit, except that he is from one-third to twice as large, has longer legs in proportion to his size, and has the most preposterous ears that ever were mounted on any creature but the jackass." (Fun fact: Black-tailed jackrabbits' extra-long ears actually help them stay cool in the desert. The blood vessels in their ears enlarge when it gets hot, causing blood to flow to their ears and ridding their bodies of excess heat.)

Rabbits, hares, and jackrabbits all have one thing in common, though: They love a good salad. So if you happen across one of these hopping creatures, give them some grass or weeds—and skip the carrots. Bugs Bunny may have loved the orange vegetable, but most hares and rabbits would prefer leafy greens.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

What Happens If I Don't Pay My Taxes on Time?

Marco Verch Professional Photo, Flickr // CC BY 2.0
Marco Verch Professional Photo, Flickr // CC BY 2.0

While death and taxes may be the only true certainties in life, somehow Tax Day always seems to sneak up on us. So what happens if tax season slips your mind, and you just don't file anything?

It depends. If you already know you're not going to get your taxes done by Tax Day, you can file for an extension. You can get an extra six months to file federal taxes by filling out a form and estimating (and paying) how much you'll owe for that year.

While you may be granted a filing extension, you are still required to pay your taxes by the regular due date: If you don't hand the IRS at least an estimated amount by April 15, you'll be charged a fee equal to .5 percent of the tax you owed in the first place per month it was left unpaid (up to 25 percent). If you ignore repeated notices from the IRS, that .5 percent increases to 1 percent per month. And you'll have to pay interest on the money you haven't given over (3 percent plus the federal short-term rate, which changes every three months, compounded each day).

If you don't file any federal income tax return at all by mid-April, you'll be slapped with a fine—5 percent of the amount you already owe for each month you're overdue, up to 25 percent. If you file your return more than two months late without a good excuse, you'll pay a minimum of $135 in penalty fees, or the balance of the tax you owe, if that total is less than $135. (According to the IRS's website, "The total penalty for failure to file and pay can be 47.5 percent [22.5 percent late filing and 25 percent late payment] of the tax owed.")

If you do a little math, you'll see that it usually pays to go ahead and file your return or get an extension, even if you can't pay your taxes immediately. Here's how Turbotax explains it:

Example: Let's say you didn't file your return or an extension by April 15, and you still owe the IRS an additional $1000.

Scenario 1: You file an extension on or before April 15 and pay your $1000 bill on April 25 (10 days late). Your penalty would be $5 (the 0.5 percent late-payment penalty applied to $1000), plus another dollar or so for the interest.

Scenario 2: You didn't file an extension, and you file your return on April 25 (10 days late) along with your $1000 payment. Your penalty would be $50 (the 5 percent late-filing penalty applied to $1000), plus another dollar or so for the interest.

Scenario 3: You file your return five years late, along with your $1000 payment. Your penalty would be around $534 (the maximum late-filing penalty of 25 percent applied to $1000, plus 5 percent interest compounded daily assuming the interest rate doesn't change).

If you don't owe any taxes because your employer withheld more than necessary and you are due to get a tax refund, you have three years to file your taxes before the IRS will keep that money. So as long as you get around to it by April 2022, you'll still get that money back. After those three years, the IRS will keep your whole refund, and it won't count toward next year's tax bill, either.

Say you just don't want to pay your taxes (a crime, just to be clear). How long before the IRS will come after you?

If your penalties and back-taxes add up to more than $25,000, someone from the IRS is going to come knocking at your door. In 2016, the IRS investigated 206 people for regularly failing to file their taxes, and put 159 people in jail for an average of three years. (Remember, it was the IRS that took down Al Capone.)

If you are a chronic non-filer and don't file your taxes even after warnings from the IRS, the government will go ahead and estimate what you owe, calculating what's called a "substitute for return." This total doesn't include deductions that you might have been eligible for, meaning that if you let the government do your taxes for you, you'll probably end up with a heftier bill.

And that's just at the federal level. While states vary on how they treat people who don't file their taxes, they slap penalties and interest on late returns and payments, too. Some states will even take your federal tax refund to pay your state back taxes. However, in many states, being approved for a federal tax extension also gets you an automatic extra six months on your state income taxes.

The lesson: If there's any chance you'll be late filing your return this year, ask for an extension ASAP.

A version of this story was first published in 2016.