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Endangered Sawfish Reproduce Through "Virgin Birth"

You know the drill: When a male and a female love each other very much—or are compelled by nature—they make a baby together. But sometimes a female becomes pregnant without any input from a male. So-called “virgin births” may seem miraculous, but they’re actually the product of parthenogenesis, a form of asexual reproduction in which an embryo grows and develops without fertilization.  

Parthenogenesis has been observed in some invertebrates like honeybees and scorpions, and very rarely among captive vertebrates like snakes, lizards, and birds. Now researchers at Stony Brook University say they’ve discovered the first known example of parthenogenesis in wild vertebrates—and the phenomenon could be more common than we think.

Named for what looks like a massive chainsaw blade protruding out of its face, the smalltooth sawfish, which lives in southern Florida, was first listed as an endangered species in 2003. Its numbers have been drastically reduced thanks to overfishing and habitat loss. Andrew Fields, a Ph.D. candidate at Stony Brook's School of Marine and Atmospheric Science, wanted to get a sense of exactly how many sawfish still exist.

“We wanted to be ready to say, ‘This is happening, and we need to do something now before they go extinct,’” Fields told mental_floss.

They may have set out to do a population count, but they found much more. As they document in Current Biology, Fields and his team examined sawfish DNA for signs of inbreeding, which can indicate a dwindling number of individuals in a species. In the process they discovered that about 3 percent of the sawfish they studied were solely the offspring of their mothers and had no genetic contribution from a male.

In normal sexual reproduction, the female egg ejects half its chromosomes through a series of cell divisions after it matures, making up the difference by combining with the chromosomes from the male sperm. In parthenogenesis, another female cell known as the polar body provides the second half of chromosomes. Although the offspring will have two sets of chromosomes, they will be identical.

Perhaps even more surprising is that the fatherless sawfish seem relatively normal. “We don’t have any physical proof they’re any different, which is strange because the general theory right now is [that] parthenogenetic offspring are not fit, and so they don’t survive in the wild,” Fields says. “So this is kind of a big step.”

But why do “virgin births” happen? Until now, sexless reproduction in vertebrates had only been observed in captivity, so the standing theory has been that the special stresses of captivity are the cause, Fields says. In 2001, for example, a hammerhead shark at a Nebraska zoo gave birth despite not having contact with a male for three years.

But these new findings suggest that maybe it’s not the stress of being in captivity that prompts parthenogenesis, but a lack of males. Perhaps a virgin birth is a dwindling species’ last-ditch effort to avoid extinction.

Unfortunately for the sawfish, parthenogenesis probably won’t help keep the population alive. While the parthenogenetic fish seem normal, they are all female, which could exacerbate the problem of male scarcity. “If the sex ratio flips enough, it could help with the extinction,” Fields says.

Fields and his team are urging other researchers to join the hunt for examples of virgin births in wild vertebrates by reexamining existing DNA evidence. “A lot of shark populations have been fished for the shark fin trade, so it’s possible we could start looking at a number of shark species,” Fields says. “It may be the data is out there, but nobody has looked for it because we think it doesn’t happen.” 

[h/t The Guardian]

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Scatterbrained
Everything You Ever Wanted to Know About Dogs
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Dogs: They’re cute, they’re cuddly … and they can smell fear!

Today on Scatterbrained, John Green and friends go beyond the floof to reveal some fascinating facts about our canine pals—including the story of one Bloodhound who helped track down 600 criminals during his lifetime. (Move over, McGruff.) They’re also looking at the name origins of some of your favorite dog breeds, going behind the scenes of the Puppy Bowl, and dishing the details on how a breed gets to compete at the Westminster Kennel Club Dog Show.

You can watch the full episode below.

For more episodes like this one, be sure to subscribe here!

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Sploot 101: 12 Animal Slang Words Every Pet Parent Should Know
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For centuries, dogs were dogs and cats were cats. They did things like bark and drink water and lay down—actions that pet parents didn’t need a translator to understand.

Then the internet arrived. Scroll through the countless Facebook groups and Twitter accounts dedicated to sharing cute animal pictures and you’ll quickly see that dogs don’t have snouts, they have snoots, and cats come in a colorful assortment of shapes and sizes ranging from smol to floof.

Pet meme language has been around long enough to start leaking into everyday conversation. If you're a pet owner (or lover) who doesn’t want to be out of the loop, here are the terms you need to know.

1. SPLOOT

You know your pet is fully relaxed when they’re doing a sploot. Like a split but for the whole body, a sploot occurs when a dog or cat stretches so their bellies are flat on the ground and their back legs are pointing behind them. The amusing pose may be a way for them to take advantage of the cool ground on a hot day, or just to feel a satisfying stretch in their hip flexors. Corgis are famous for the sploot, but any quadruped can do it if they’re flexible enough.

2. DERP

Person holding Marnie the dog.
Emma McIntyre, Getty Images for ASPCA

Unlike most items on this list, the word derp isn’t limited to cats and dogs. It can also be a stand-in for such expressions of stupidity as “duh” or “dur.” In recent years the term has become associated with clumsy, clueless, or silly-looking cats and dogs. A pet with a tongue perpetually hanging out of its mouth, like Marnie or Lil Bub, is textbook derpy.

3. BLEP

Cat laying on desk chair.
PoppetCloset, Flickr // CC BY-NC-ND 2.0

If you’ve ever caught a cat or dog poking the tip of its tongue past its front teeth, you’ve seen a blep in action. Unlike a derpy tongue, a blep is subtle and often gone as quickly as it appears. Animal experts aren’t entirely sure why pets blep, but in cats it may have something to do with the Flehmen response, in which they use their tongues to “smell” the air.

4. MLEM

Mlems and bleps, though very closely related, aren’t exactly the same. While blep is a passive state of being, mlem is active. It’s what happens when a pet flicks its tongue in and out of its mouth, whether to slurp up water, taste food, or just lick the air in a derpy fashion. Dogs and cats do it, of course, but reptiles have also been known to mlem.

5. FLOOF

Very fluffy cat.
J. Sibiga Photography, Flickr // CC BY-NC-ND 2.0

Some pets barely have any fur, and others have coats so voluminous that hair appears to make up most of their bodyweight. Dogs and cats in the latter group are known as floofs. Floofy animals will famously leave a wake of fur wherever they sit and can squeeze through tight spaces despite their enormous mass. Samoyeds, Pomeranians, and Persian cats are all prime examples of floofs.

6. BORK

Dog outside barking.
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According to some corners of the internet, dogs don’t bark, they bork. Listen carefully next time you’re around a vocal doggo and you won’t be able to unhear it.

7. DOGGO

Shiba inu smiling up at the camera.
iStock

Speaking of doggos: This word isn’t hard to decode. Every dog—regardless of size, floofiness, or derpiness—can be a doggo. If you’re willing to get creative, the word can even be applied to non-dog animals like fennec foxes (special doggos) or seals (water doggos). The usage of doggo saw a spike in 2016 thanks to the internet and by the end of 2017 it was listed as one of Merriam-Webster’s “Words We’re Watching.”

8. SMOL

Tiny kitten in grass.
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Some pets are so adorably, unbearably tiny that using proper English to describe them just doesn’t cut it. Not every small pet is smol: To earn the label, a cat or dog (or kitten or puppy) must excel in both the tiny and cute departments. A pet that’s truly smol is likely to induce excited squees from everyone around it.

9. PUPPER

Hands holding a puppy.
iStock

Like doggo, pupper is self-explanatory: It can be used in place of the word puppy, but if you want to use it to describe a fully-grown doggo who’s particularly smol and cute, you can probably get away with it.

10. BOOF

We’ve already established that doggos go bork, but that’s not the only sound they make. A low, deep bark—perhaps from a dog that can’t decide if it wants to expend its energy on a full bark—is best described as a boof. Consider a boof a warning bark before the real thing.

11. SNOOT

Dog noses poking out beneath blanket.
iStock

Snoot was already a dictionary-official synonym for nose by the time dog meme culture took the internet by storm. But while snoot is rarely used to describe human faces today, it’s quickly becoming the preferred term for pet snouts. There’s even a wholesome viral challenge dedicated to dogs poking their snoots through their owners' hands.

12. BOOP

Have you ever seen a dog snoot so cute you just had to reach out and tap it? And when you did, was your action accompanied by an involuntary “boop” sound? This urge is so universal that boop is now its own verb. Humans aren’t the only ones who can boop: Search the word on YouTube and treat yourself to hours of dogs, cats, and other animals exchanging the love tap.

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