How Did the Duck Hunt Gun Work?

For many children of the '80s, a good portion of your childhood probably revolved around sitting too close to the TV, clutching a plastic safety cone-colored hand gun and blasting waterfowl out of a pixilated sky in Duck Hunt (also, trying to blow that dog’s head off when he laughed at you). The Duck Hunt gun, officially called the Nintendo Entertainment System (NES) Zapper, seems downright primitive next to the Nintendo’s Wii and Microsoft’s Kinect, but in the late 80s, it filled plenty of young heads with wonder. How did that thing work?

Annie get your Zapper

The Zapper’s ancestry goes back to the mid 1930s, when the first so-called “light guns” appeared after the development of light-sensing vacuum tubes. In the first light gun game, Ray-O-Lite (developed in 1936 by Seeburg, a company that made parts and systems for jukeboxes), players shot at small moving targets mounted with light sensors using a gun that emitted a beam of light. When the beam struck a sensor, the targets – ducks, coincidentally – registered the “hit” and a point was scored.

Light guns hit home video game consoles with Shooting Gallery on the Magnavox Odyssey in 1972. Because the included shotgun-style light gun was only usable on a Magnavox television, the game flopped. The Nintendo Entertainment System (NES) Zapper then fell into the hands of American kids in October 1985, when it was released in a bundle with the NES, a controller and a few games. Early versions of the peripheral were dark gray, but the color of the sci-fi ray gun-inspired Zapper was changed a few years later when a federal regulation required that toy and imitation firearms be “blaze orange” (color #12199, to be exact) so they wouldn’t be mistaken for the real deal.

While there were a number of Zapper-compatible games released for the NES (when I was a kid and my dad worked from home, we wasted plenty of afternoons away playing Hogan’s Alley), most lived in the shadow of the iconic Duck Hunt, the most recognizable and popular Zapper game.

Gone in a Flash

While older light guns like the Ray-O-Lite rifle emitted beams of light, the Zapper and many other recent light guns work by receiving light through a photodiode on or in the barrel and using that light to figure out where on the TV screen you're aiming.

When you point at a duck and pull the trigger, the computer in the NES blacks out the screen and the Zapper diode begins reception. Then, the computer flashes a solid white block around the targets you’re supposed to be shooting at. The photodiode in the Zapper detects the change in light intensity and tells the computer that it’s pointed at a lit target block — in others words, you should get a point because you hit a target. In the event of multiple targets, a white block is drawn around each potential target one at a time. The diode’s reception of light combined with the sequence of the drawing of the targets lets the computer know that you hit a target and which one it was. Of course, when you’re playing the game, you don’t notice the blackout and the targets flashing because it all happens in a fraction of a second.

This target flashing method helped Nintendo overcome a weakness of older light gun games: cheaters racking up high scores by pointing the gun at a steady light source, like a lamp, and hitting the first target right out of the gate.

If you’re hungry for a more technical depth, check out Nintendo's 1989 patent on the Zapper technology

Big Questions
Do Bacteria Have Bacteria?

Drew Smith:

Do bacteria have bacteria? Yes.

We know that bacteria range in size from 0.2 micrometers to nearly one millimeter. That’s more than a thousand-fold difference, easily enough to accommodate a small bacterium inside a larger one.

Nothing forbids bacteria from invading other bacteria, and in biology, that which is not forbidden is inevitable.

We have at least one example: Like many mealybugs, Planococcus citri has a bacterial endosymbiont, in this case the β-proteobacterium Tremblaya princeps. And this endosymbiont in turn has the γ-proteobacterium Moranella endobia living inside it. See for yourself:

Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)
Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)

I don’t know of examples of free-living bacteria hosting other bacteria within them, but that reflects either my ignorance or the likelihood that we haven’t looked hard enough for them. I’m sure they are out there.

Most (not all) scientists studying the origin of eukaryotic cells believe that they are descended from Archaea.

All scientists accept that the mitochondria which live inside eukaryotic cells are descendants of invasive alpha-proteobacteria. What’s not clear is whether archeal cells became eukaryotic in nature—that is, acquired internal membranes and transport systems—before or after acquiring mitochondria. The two scenarios can be sketched out like this:

The two hypotheses on the origin of eukaryotes:

(A) Archaezoan hypothesis.

(B) Symbiotic hypothesis.

The shapes within the eukaryotic cell denote the nucleus, the endomembrane system, and the cytoskeleton. The irregular gray shape denotes a putative wall-less archaeon that could have been the host of the alpha-proteobacterial endosymbiont, whereas the oblong red shape denotes a typical archaeon with a cell wall. A: archaea; B: bacteria; E: eukaryote; LUCA: last universal common ancestor of cellular life forms; LECA: last eukaryotic common ancestor; E-arch: putative archaezoan (primitive amitochondrial eukaryote); E-mit: primitive mitochondrial eukaryote; alpha:alpha-proteobacterium, ancestor of the mitochondrion.

The Archaezoan hypothesis has been given a bit of a boost by the discovery of Lokiarcheota. This complex Archaean has genes for phagocytosis, intracellular membrane formation and intracellular transport and signaling—hallmark activities of eukaryotic cells. The Lokiarcheotan genes are clearly related to eukaryotic genes, indicating a common origin.

Bacteria-within-bacteria is not only not a crazy idea, it probably accounts for the origin of Eucarya, and thus our own species.

We don’t know how common this arrangement is—we mostly study bacteria these days by sequencing their DNA. This is great for detecting uncultivatable species (which are 99 percent of them), but doesn’t tell us whether they are free-living or are some kind of symbiont. For that, someone would have to spend a lot of time prepping environmental samples for close examination by microscopic methods, a tedious project indeed. But one well worth doing, as it may shed more light on the history of life—which is often a history of conflict turned to cooperation. That’s a story which never gets old or stale.

This post originally appeared on Quora. Click here to view.

Big Questions
Why Do Cats 'Blep'?

As pet owners are well aware, cats are inscrutable creatures. They hiss at bare walls. They invite petting and then answer with scratching ingratitude. Their eyes are wandering globes of murky motivations.

Sometimes, you may catch your cat staring off into the abyss with his or her tongue lolling out of their mouth. This cartoonish expression, which is atypical of a cat’s normally regal air, has been identified as a “blep” by internet cat photo connoisseurs. An example:

Cunning as they are, cats probably don’t have the self-awareness to realize how charming this is. So why do cats really blep?

In a piece for Inverse, cat consultant Amy Shojai expressed the belief that a blep could be associated with the Flehmen response, which describes the act of a cat “smelling” their environment with their tongue. As a cat pants with his or her mouth open, pheromones are collected and passed along to the vomeronasal organ on the roof of their mouth. This typically happens when cats want to learn more about other cats or intriguing scents, like your dirty socks.

While the Flehmen response might precede a blep, it is not precisely a blep. That involves the cat’s mouth being closed while the tongue hangs out listlessly.

Ingrid Johnson, a certified cat behavior consultant through the International Association of Animal Behavior Consultants and the owner of Fundamentally Feline, tells Mental Floss that cat bleps may have several other plausible explanations. “It’s likely they don’t feel it or even realize they’re doing it,” she says. “One reason for that might be that they’re on medication that causes relaxation. Something for anxiety or stress or a muscle relaxer would do it.”

A photo of a cat sticking its tongue out

If the cat isn’t sedated and unfurling their tongue because they’re high, then it’s possible that an anatomic cause is behind a blep: Johnson says she’s seen several cats display their tongues after having teeth extracted for health reasons. “Canine teeth help keep the tongue in place, so this would be a more common behavior for cats missing teeth, particularly on the bottom.”

A blep might even be breed-specific. Persians, which have been bred to have flat faces, might dangle their tongues because they lack the real estate to store it. “I see it a lot with Persians because there’s just no room to tuck it back in,” Johnson says. A cat may also simply have a Gene Simmons-sized tongue that gets caught on their incisors during a grooming session, leading to repeated bleps.

Whatever the origin, bleps are generally no cause for concern unless they’re doing it on a regular basis. That could be sign of an oral problem with their gums or teeth, prompting an evaluation by a veterinarian. Otherwise, a blep can either be admired—or retracted with a gentle prod of the tongue (provided your cat puts up with that kind of nonsense). “They might put up with touching their tongue, or they may bite or swipe at you,” Johnson says. “It depends on the temperament of the cat.” Considering the possible wrath involved, it may be best to let them blep in peace.

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