10 Notable Gestation Periods in the Animal Kingdom

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The gestation periods of the animal kingdom are varied and fascinating. Some clock in at just a few weeks, making any human green with envy, while others can last more than a year. Here are 10 notable gestation times for animals around the globe. The lesson? Be thankful that you’re not a pregnant elephant.

1. ELEPHANTS: 640-660 DAYS

Elephants are pregnant for a long time. Like really, really long. At an average of 95 weeks, the gestation period is more than double the length of a human pregnancy, so it shouldn't come as a shock that female elephants don't often have more than four offspring during their lifetimes. Who has the time?

2. HIPPOS: 8 MONTHS

A photo of a mother hippo and her baby in Uganda

Yes, it takes less time to make a hippopotamus than it takes to make a human.

3. GIRAFFE: 14-15 MONTHS

Baby giraffes can weigh more than 150 pounds and can be around 6 feet tall. Another fascinating tidbit: giraffes give birth standing up, so it's pretty normal for a baby to fall 6 feet to the ground.

4. KILLER WHALE: 17 MONTHS

There’s a reason for the long wait: after that 17 months, Baby Shamu emerges weighing anywhere from 265 to 353 pounds and measuring about 8.5 feet long. Yikes.

5. OPOSSUM: 12-13 DAYS

A baby opossum wrapped up in a blanket

Blink and you'll miss it: This is the shortest gestation period of any mammal in North America. But since the lifespan of an opossum is only two to four years, it makes sense.

6. GERBILS: 25 DAYS

Hey, they get off pretty easy.

7. GORILLAS: 8.5 MONTHS

It's not a huge surprise that their gestational periods are pretty similar to ours, right?

8. BLACK BEAR: 220 DAYS

A pair of black bear cubs

Also less than a human. Interestingly, cubs might only be 6 to 8 inches in length at birth and are completely hairless. 

9. PORCUPINE: 112 DAYS

This is the longest gestation period of any rodent. Thankfully for the mother, porcupine babies (a.k.a. porcupettes) are actually born with soft quills, and it's not until after birth that they harden up.

10. WALRUS: 15 MONTHS

Baby walruses? Kind of adorable. They certainly take their sweet time coming out, though.

What's the Difference Between Pigeons and Doves?

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To the layman, the difference between pigeons and doves has something to with color, maybe. Or location. Or general appeal (doves usually get much better press than pigeons do). But what’s the actual, scientific difference between doves and pigeons?

As it turns out, there isn’t one. Paul Sweet, the collection manager for the department of ornithology at the American Museum of Natural History, says the difference is more linguistic than taxonomic.

“The word dove is a word that came into English from the more Nordic languages, whereas pigeon came into English from French,” Sweet tells Mental Floss.

Both dove and pigeon refer to the 308 species of birds from the Columbidae family, Sweet says. There’s no difference between a pigeon and a dove in scientific nomenclature, but colloquial English tends to categorize them by size. Something called a dove is generally smaller than something called a pigeon, but that’s not always the case. A common pigeon, for example, is called both a rock dove and a rock pigeon.

“People just have their own classification for what makes them different,” Sweet says. “So in the Pacific, for example, the big ones might get called pigeons and the smaller ones might be called doves, but they’re actually more closely related to each other than they are to other things in, say, South America, that are called pigeons and doves.”

The difference boils down to linguistic traditions, so feel free to tell people you’re releasing pigeons at your wedding or that you’re feeding doves in the park. Scientifically speaking, you’ll be correct either way.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

8 Hair-Raising Facts About Black Cats

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No member of catkind is more maligned than the black cat. At best, they're bemoaned as lackluster photography subjects; at worst, they're seen as harbingers of really bad luck. But there's a lot to love about these furballs, as evidenced by the holidays in their honor—the ASPCA celebrates Black Cat Appreciation Day annually on August 17 and, across the pond, October 27 is National Black Cat Day—and the facts below.

1. IN SOME CULTURES, BLACK CATS ARE GOOD LUCK.

A black kitten stretching
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They may have a less-than-stellar reputation in some areas of the world, but there are plenty of places where black cats aren’t bad luck at all. If you’re a single woman in Japan, owning a black cat is said to increase your number of suitors; if you’re in Germany and one crosses your path from right to left, good things are on the horizon.

2. THEY'RE A SAILOR'S BEST FRIEND.

Not only were cats welcome aboard British vessels to hunt mice, but sailors generally thought a black cat in particular would bring good luck and ensure a safe return home. A few of these kitties have been enshrined in maritime history, like Tiddles, who traveled more than 30,000 miles during his time with the Royal Navy. (His favorite pastime was playing with the capstan’s bell-rope.)

3. THERE IS NO ONE BLACK CAT BREED.

The Cat Fanciers’ Association (CFA) recognizes 22 different breeds that can have solid black coats—including the Norwegian Forest Cat, Japanese Bobtail, and Scottish Fold—but the Bombay breed is what most people picture: a copper-eyed, all-black shorthair. The resemblance to a "black panther" (more on those animals in a bit) is no coincidence. In the 1950s, a woman named Nikki Horner was so enamored with how panthers looked that she bred what we now refer to as the Bombay.

4. BLACK CATS ARE AS EASILY ADOPTED AS CATS OF OTHER COLORS.

Black cat facts.
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It’s common to think that black cats in shelters are the last in line to find their forever homes, but a recent survey from the ASPCA suggests otherwise. Although euthanasia numbers for black cats were some of the highest, their total number of adoptions was the highest of any hue as well. The vet who conducted the study argues that there may just simply be more black cats than other colors.

5. THEIR COATS CAN "RUST."

A black cat’s color all boils down to a genetic quirk. There are three variants of the black fur gene (solid black, brown, and cinnamon), and the hue works in conjunction with the pattern. If a cat has a solid black hue, but also the dominant tabby stripe gene, heavy exposure to the sun can make the eumelanin pigment in its fur break down to reveal its once-invisible stripes (another potential cause: nutritional deficiency). What was once a black cat is now a rusty brown cat.

6. THE GENE THAT CAUSES BLACK FUR MIGHT MAKE THESE FELINES RESISTANT TO DISEASE.

Even though their coloring is what gives them a bad reputation, these felines may be getting the last laugh after all. The mutation that causes a cat’s fur to be black is in the same genetic family as genes known to give humans resistance to diseases like HIV. Some scientists think the color of these cats may have less to do with camouflage and more to do with disease resistance. They’re hoping that as more cat genomes are mapped, we may get a step closer to curing HIV.

7. YOU CAN VISIT A CAT CAFE DEVOTED TO BLACK CATS.

Step through the doors of Nekobiyaka in Himeji, Japan and get ready for your wildest cat lady dreams to come true. Black cats are the stars of this café and visitors are invited to pet (but not pick up) these lithe felines. Each of Nekobiyaka’s identical-looking black cats wears a different colored bandana to resolve any catastrophic mix-ups.

8. THEY'RE DIFFICULT TO PHOTOGRAPH—BUT IT CAN BE DONE.

A black cat is photographed against a blue-gray background
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The modern-day conundrum black cat owners face isn’t bad luck, but bad lighting. In a world filled with people sharing photos of their pets on Instagram, black cats can end up looking like a dark blob in photos. One photographer’s advice? Minimalist backgrounds, so your subject can stand out, and angling them towards natural light sources (but keep them out of bright sunlight!). If you're snapping pics on your iPhone, tap on your cat's face, then use the sun icon to brighten up the photo.

BONUS: BLACK PANTHERS HAVE SPOTS.

Technically, there is no such thing as a black panther—it’s a term used for any big black cat. What we call black panthers are in fact jaguars or leopards and yes, they have spots, too. Their hair shafts produce too much melanin thanks to a mutation in their agouti genes, which are responsible for distributing pigment in an animal’s fur. Look carefully and you can see a panther’s spots as the sunlight hits them in just the right way.

This article originally ran in 2016.

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