How Mogwai and Gremlins Work

Celebrity mogwai Gizmo is not amused.
© Warner Brothers/courtesy Everett Collection

If you're a child of the 1980s, then chances are you once owned a pet mogwai. Even now, you probably remember the overwhelming thrill you felt when you tore away the gift wrap and discovered a diminutive, furry humanoid nestled at the bottom of a shoebox.

Assuming you were an organized, dependable sort of kid, then chances are you still share a loving, regimented life with your mogwai to this day. Perhaps the little guy's seated next to you on the couch right now, quietly filling out The New York Times crossword puzzle with a miniature golf pencil.


But if you were like most children -- which is to say irresponsible and easily distracted -- then the whole mogwai experience probably ended in tears. First came the rapid asexual reproduction, followed by grotesque metamorphosis. Before you knew what happened, mom was crying and every appliance in the kitchen had a dead gremlin in it.

Such are the lessons of childhood, right? All pets come with rules and responsibilities: replenish the food bowl, empty the litter box, take the dog on a walk. But mogwai come with their own bizarre set of mandates. Remember these?

  1. Keep your mogwai away from bright lights, especially sunlight.
  2. Never allow your mogwai to get wet.
  3. Never feed your mogwai after midnight.

Today, your chances of buying a pet mogwai are slim. After the great gremlins disaster of 1990, most countries banned or strictly prohibited the importation, release or exportation of specimens. Ownership, while still legal, is subject to strict federal regulation.

But that doesn't mean you shouldn't know how these amazing creatures work, as well as how they may have come to exist.


Mogwai and Gremlin Reproduction

Asexual budding: Just add water.

As you've probably noticed, the life cycle of the mogwai is something of a train wreck. While these creatures initially seem to be our own evolutionary kin, their strange biology differs drastically from pretty much everything else on Earth.

Standing roughly 9 inches (23 centimeters) tall, mogwai closely resemble many members of the primate order. They boast the bipedal stature of a squat human, the large eyes of a spectral tarsier and the enormous ears of an aye-aye lemur. Like all primates, mogwai are warm-blooded vertebrates, but that's where the similarities end.


For starters, you can shave a mogwai bare (not recommended) and you won't find a single nipple on its body. This alone doesn't disqualify them from mammal status, since egg-laying monotreme mammals such as the platypus and the echidna lactate through primitive skin openings. But you won't even find mammary glands on a mogwai -- and for a very good reason.

Mogwai are asexual and reproduce through a process known as budding. Various flatworms, sponges and corals also reproduce this way, but perhaps the best multicellular organism of comparison is the freshwater hydra. These tiny, tentacled creatures generally grow to lengths of between 0.6 and 1.2 inches (15 and 30 millimeters). If food and water are plentiful, then the hydra grows a series of small bumps (or buds) on its body. These bumps develop into miniature hydras that eventually pinch off from the parent organism to fend for themselves.

A healthy hydra may produce new offspring every three to four days. With mogwai, the budding process is more rapid. If a well-nourished mogwai's skin comes into contact with even a small amount of liquid water, several furry balls bud from the creature's back and pinch free from the parent mogwai as independent organisms -- all in less than a minute.

The budding process is extremely unpleasant for the parent mogwai, sapping it of vital energy and body mass. For weaker mogwai, the process can even prove fatal. Fortunately, the creature's ravenous hunger and high metabolism make for a rather speedy recovery.


Mogwai and Gremlin Metamorphosis

Chicken after midnight: Not a good idea.

While the mogwai budding cycle can certainly continue in a closed circle, another important biological event defines the mogwai life cycle: metamorphosis.

While other vertebrates such as amphibians regularly undergo metamorphic changes, the mogwai/gremlins' potential transformation differs dramatically from that of tadpoles and frogs. In fact, the entire process closely resembles the change we see when a caterpillar turns into a butterfly.


When a mogwai gorges after midnight (more on this later), it cocoons itself inside a chrysalis formed from secreted bile and its own hair. Within this leathery shell, the creature essentially melts. Enzymes break most of the mogwai's body down into a rich bath of imaginal cells. Like stem cells, imaginals can differentiate into other cell types. As with a caterpillar's transformation, these cells serve as the building blocks of the organism's new body

What emerges from the chrysalis is, of course, a gremlin. Although the creature retains some of its mogwai facial and cranial features (plus all of its prior memories), the rest is startlingly different.

While the mogwai is furry and omnivorous, the reptilian-looking gremlin is largely hairless and geared toward a more predatory, carnivorous lifestyle. Its claws and teeth easily tear flesh. Its enhanced strength, speed and dexterity enable it to apprehend prey and more effectively fend for itself against other animals. Given the choice, however, it's also perfectly happy to steal pizza and beer.

Curiously enough, the gremlin also undergoes asexual budding but only produces gremlin-stage offspring in the process. How then, you might ask, would this perplexing life cycle ever come back around to the cuddly mogwai? Think back to the hydra: This tiny freshwater predator is capable of both sexual and asexual reproduction.

Is it possible that mogwai/gremlins were once capable of sexual reproduction as well, enabling even fully developed gremlins to mate and produce mogwai offspring? If this theory holds true, it means the creatures gradually lost the ability to sexually reproduce and depend exclusively on asexual budding for propagation -- a reality that might eventually eliminate mogwai altogether.


Like a Gremlin in the Sun

The gremlin form
Image courtesy of Mike Corriero

Like many nocturnal creatures, mogwai and gremlins are incredibly photosensitive. Yet even the eyeless, subterranean olm salamander merely changes color if exposed to direct sunlight. Ultraviolet (UV) rays can kill most bacteria, but such a reaction is unheard of in larger organisms.

Except for the mogwai/gremlin species, of course. Let in a little sunlight and they immediately fester and melt into a grotesque green sludge.


For most people, the only real comparison is the reaction we see when a particularly morbid (or curious) child pours salt on a slug: The salt crystals draw vital moisture out of the slimy creature, effectively dehydrating it to death. But that's not what happens when a gremlin melts.

If you'll think back to the mogwai's metamorphosis into gremlinhood, you'll remember the process closely resembles a caterpillar's transformation into a butterfly. Once cocooned in their chrysalises, both caterpillars and mogwai produce an enzyme that breaks their bodies down into a rich bath of imaginal cells. Those cells ultimately reconstitute the creature's metamorphosed form.

When exposed to direct sunlight, the mogwai/gremlin body produces this exact enzyme, essentially causing the body to digest itself -- only outside the safety of the chrysalis. Needless to say, it's quite an excruciating mode of death for a gremlin or mogwai, especially since the creature remains conscious even after the process reduces it to a pile of slime, bones and brain.

Scientists are still unclear why this disgusting physical reaction takes place, but most signs point to it being a congenital mutation common to all mogwai and gremlins. Other aspects of the creature's life cycle are dependent on solar activity. In fact, as we'll explore on the next page, the position of the sun partially triggers a mogwai's remarkable metamorphosis.


Food After Midnight

Follow the rules.
Art courtesy of Tom Whalen

We all know better than to feed a mogwai after midnight. Even the creatures themselves (or at least the more intelligent specimens) seem to understand the wages of 3 a.m. nachos: complete metamorphosis.

Needless to say, "after midnight" is a bit vague, especially when you factor in time zones. To be clear, the ingestion of food only triggers gremlin metamorphosis in the hours immediately following solar midnight, the opposite of solar noon. In other words, regardless of what the clock says, it all comes down to the position of the sun in relation to the mogwai's location. In fact, over the course of a year, solar midnight rarely lines up with clock midnight and depends instead on longitude and season.


How does the mogwai's body know when solar midnight occurs? As with most animals, it comes down to the creature's circadian rhythm, a 24-hour physiological cycle present in most organisms. Far more than a mere pattern for wakefulness and sleep, it affects a host of biological processes, including hormone production and cell and brain activity. While mostly dependent on the solar cycle, light levels and temperature also modulate circadian rhythm.

Brazilian big-eyed bats (Chiroderma doriae) and urban European hedgehogs (Erinaceus europaeus) both engage in post-midnight feeding activity, all thanks to the "programming" of their circadian rhythms. It's the same with mogwai: Their circadian rhythm triggers the hormonal functions responsible for full metamorphosis. During this state they're essentially primed for transformation -- all they need is a huge meal to trigger the change.

Why do midnight feedings trigger the change? We'll discuss the theories on the next page.


Gremlin Origin Theories I

Remember: Mogwai are contraband.
Art courtesy of Tom Whalen

While the creatures didn't become a mainstream phenomenon until the 1980s, mogwai accounts date back to ancient China. In modern times, gremlin infestations plagued military operations throughout World War II. In fact, most experts agree that this global military conflict allowed stowaway gremlins and contraband mogwai to spread across the world.

But why are these organisms so peculiar? Where do they come from? The theories range from ridiculous yarns about alien wizards to divine lessons in virtue and temptation. We'll briefly explore the three leading theories:


Naturalist theory: Most scientists hold that for all their strangeness, mogwai and gremlins are a naturally occurring species. As we've explored in this article, they might be the oddest land vertebrates on Earth, but their biological processes are less strange when you take in the planet's diversity. Over the course of their evolution, they've lost their ability to reproduce sexually -- and might well have lost their larval mogwai stage entirely if not for human intervention. The resulting lack of genetic diversity allowed a congenital photosensitivity mutation to dominate the species.

Human intervention is key to understanding the naturalist theory of gremlins. While the creatures may seem unbalanced and ecologically dangerous, we have to remember that human beings allowed them to spread around the globe -- much as we've spread such devastating invasive species as the lionfish, kudzu and domestic cats. Also, both gremlin budding and metamorphosis depend on ready access to food and water -- commodities less prevalent in, say, China's Gobi Desert than the modern human home.

So who's the real monster? The ecosystem-wrecking humans or the mogwai with a love for late-night snacks and occasional Broadway performances of "New York, New York"?

I think we both know the answer.


Gremlin Origin Theories II

Are mogwai an alien bioweapon? Are they really that different from our old friend the xenomorph?
Travis Falligant/Creative Commons

With the naturalist theory out of the way, it's time to think cosmically about gremlin and mogwai origins.

Extraterrestrial theory: Simply put, this theory argues that mogwai and gremlins differ dramatically from terrestrial modes of life because they're not native to our planet. For instance, they may have evolved on a much dryer world, where the occasional wet season or plentiful water source served as a call for massive asexual reproduction. Their circadian metamorphosis cycle might make more sense on their planet of origin -- perhaps a world of epically long days and nights. On such a planet, their furry mogwai form might allow the creatures to survive chilly seasons of night. Likewise, their post-midnight metamorphosis would have originally ensured that the creatures didn't mature into their hairless adult forms until the warmer day-season approached. Sadly, we won't know the answer to these questions until we actually discover such a theorized gremlin home world.


Biological weapon theory: Finally, some scientists point to the gremlin's destructive nature as proof positive of its origins as an extraterrestrial biological weapon. Think about it: They reproduce like wildfire and have a tendency to wreck everything in sight. Oh, and they initially take the form of an irresistibly adorable snuggle buddy before transforming into a murderous monster. If left unchecked by human efforts, the creatures would quickly overrun terrestrial ecosystems and convert all available organic material into gremlin flesh. In short, they are invasive and unsustainable because they were genetically engineered to eradicate all life on Earth.

Who would unleash such a weapon? And why? Did some advanced species of engineers decide that life on Earth was headed in a disastrous direction? Is it any wonder that gremlins spread so rapidly during the 20th century, as war raged around the globe and humans entered the Atomic Age? These questions remain unanswered, but if mogwai and gremlins were invented to destroy us, we should thank our lucky stars that they melt in sunshine and are also so easily distracted by costumes, movies and musical numbers.


Author's Note

Senior Staff Writer Robert Lamb
HowStuffWorks 2009

This article was my follow-up to How the 'Alien' Xenomorph Works, and while H.R. Giger's biomechanical monster is far cooler, the gremlins proved a lot more exciting to write about. After all, the xenomorph biology is fairly rooted in actual science, and its real-world parallels are many. The gremlin, however, is just rampant silliness.

But I embraced the challenge, surprised myself with some of the scientific tie-ins I discovered and managed to produce what may be the first scientific theory of mogwai and gremlins on the Net. I think about this stuff and perform Google image searches for "gremlin nipples" so you don't have to.


An article like this, by its very nature, can never be 100 percent watertight -- especially if you start bringing up examples from 1990's "Gremlins 2: The New Batch," which saw a gremlin turn into a bolt of lightning. You have to take all things gremlin-related with a grain of salt; though you can rest assured that all comparisons to real-world organisms are researched and accurate.

Related Articles


  • Acton, Q. Ashton. "Issues in Animal Science and Research: 2011 Edition." Scholarly Editions. 2012.
  • Brower, Lincoln. "Inside the Chrysalis." Journey North. (Aug. 21, 2012)
  • "Gremlins." Warner Bros. 1984.
  • "Gremlins 2: The New Batch." Warner Bros. 1990.
  • Harmon, Katherine. "Confused circadian rhythm could increase triglycerides." Scientific American. Aug. 3, 2010. (Aug. 21, 2012)
  • Morgan, Mike. "Hydra" Microscopy UK. 1996. (Aug. 21, 2012)
  • Smith, David. "Hall of Mammals." The University of California Museum of Paleontology. July 9, 1997. (Aug. 21, 2012)
  • Smithsonian National Zoological Park. "The Unique Characteristics of Primates." (Aug. 21, 2012)
  • Stangl, Chris. "A Pox On Morgturmen!: George Gipe's GREMLINS Novelization." The Exploding Kinetoscope. Feb. 27, 2006. (Aug. 21, 2012)