50 Fun Facts About Halloween Science

Bats are the only mammals capable of what?

Flying squirrels only glide. Bats make up about a fifth of all mammal species, with at least 1,500 kinds.

Roughly what share of all mammal species are bats?

They are the second-largest order of mammals after rodents.

How many bat species feed only on blood?

The common, hairy-legged and white-winged vampire bats, all in Latin America. The 'spectral vampire bat', despite its name, eats other animals.

What is draculin, found in vampire bat saliva?

It stops the victim's blood clotting while the bat laps it up, and it is being studied as a stroke drug.

How many limbs does a spider have?

That is what makes them arachnids, not insects. Their body is fused into just two segments.

Weight for weight, spider silk is stronger than steel but not as strong as what?

Its trick is combining high tensile strength with stretchiness, which is why webs absorb the impact of flying insects.

How long have spider webs existed, judging from a piece of amber found in Sussex, England?

The Early Cretaceous amber preserved silk strands from the age of dinosaurs.

What are the irritating 'urticating hairs' that many New World tarantulas can flick at attackers?

They irritate skin and can damage eyes. The goliath birdeater can weigh 170 grams with a 30 cm leg span.

Botanically, a pumpkin is a cultivated what?

It belongs to the genus Cucurbita and its fruit is technically a berry called a pepo.

How heavy was the record pumpkin set in October 2023?

That is 2,749 pounds. Ordinary carving pumpkins weigh 3 to 8 kilograms.

Before pumpkins, what were jack-o'-lanterns carved from in Ireland?

Irish legend has Stingy Jack roaming the earth with a hollowed turnip for a lamp. Pumpkins took over in America.

The name jack-o'-lantern originally described which natural phenomenon?

Also known as will-o'-the-wisps or ignis fatuus, 'foolish fire', probably from marsh gas igniting.

Why do apples float, making apple bobbing possible?

The tradition goes back to Roman times, when the first to bite an apple was said to be next to marry.

What is the scientific term for the excess dark pigment that makes a black cat black?

Black leopards and jaguars have the same trait, which helps them hunt at night. In Britain a black cat is good luck.

In which region is a black cat crossing your path considered good luck rather than bad?

The RSPCA confirmed in 2014 that in UK folklore black cats symbolise good luck. They are still adopted less than other cats.

Which physiologist first described the 'fight or flight' response, in 1914?

The adrenal medulla floods the body with adrenaline and noradrenaline. It is now often called fight, flight or freeze.

Which almond-shaped brain structure in the temporal lobes is central to processing fear?

Human screams have a special acoustic 'roughness' that lights it up directly.

Which acoustic property of human screams selectively activates the brain's danger centre, per Luc Arnal?

Roughness is a fast modulation of the sound that the brain treats as an alarm signal.

What tiny muscles contract to give you goosebumps when you are frightened or cold?

They pull each hair upright. It is thought to be a vestigial reflex from when our ancestors had fur to fluff up.

Which organs produce most of the body's adrenaline?

They sit on top of the kidneys. A few neurons in the medulla oblongata make some too.

Dry ice, used for spooky fog, is the solid form of which gas?

It has no liquid state at normal pressure, so it goes straight from solid to gas.

At what temperature does dry ice sublimate at normal atmospheric pressure?

That is about -109°F. Liquid nitrogen is the one at -196°C.

What kind of reaction makes a glow stick glow?

Two chemicals mix when you snap the inner vial. It is 'cold light', using no electricity, which is why they are safe near gas.

Firefly light comes from an enzyme acting on a substrate. What is the enzyme called?

Luciferase oxidises luciferin. Fireflies are actually beetles, and some females fake other species' flashes to eat the males.

How far can an owl rotate its head?

They have 14 neck vertebrae to our seven, and their eyes are fixed in their sockets, so they have to turn their whole head.

How many neck vertebrae does an owl have?

Their blood vessels are also adapted so the twist does not cut off supply to the brain.

The 'zombie-ant fungus' Ophiocordyceps unilateralis was discovered in 1859 by which British naturalist?

It hijacks carpenter ants' behaviour before killing them, and inspired the infection in The Last of Us.

Toxoplasma gondii alters rodent behaviour so they are more likely to be eaten by which animals?

Cats are the only hosts in which the parasite can reproduce sexually, so making mice careless around cats serves the parasite.

The 'corpse flower' Amorphophallus titanum smells of rotting flesh in order to attract what?

It is native to Sumatra and blooms rarely and briefly, drawing crowds to botanic gardens when it does.

Chocolate is toxic to dogs because of which compound?

Dark and baking chocolate contain far more than milk chocolate. It has a ten-hour half-life in the body.

How many bones are in an adult human skeleton?

Babies are born with around 270, but many fuse together as they grow.

How quickly after death can rigor mortis begin?

It is caused by chemical changes in the muscles, mainly involving calcium, and is the fourth recognised stage of death.

How many stages of decomposition are typically recognised in vertebrates?

Fresh, bloat, active decay, advanced decay and dry or skeletonised. Forensic investigators use them to estimate time of death.

Cadaverine, the foul compound of rotting bodies, comes from the breakdown of which amino acid?

Small amounts exist in living tissue too. Its partner in crime, putrescine, comes from ornithine.

What have reviews and meta-analyses concluded about the full moon's effect on human behaviour?

Studies of thousands of births and emergency-room visits keep finding nothing. The 'lunar effect' is folklore.

What is the medical condition sometimes called 'werewolf syndrome'?

It causes abnormal hair growth all over the body. Barbara van Beck, born in 1629, was one of the first people depicted with it.

A 'witch's broom' in a tree is what?

Fungi, mites and viruses can all cause it. Some dwarf conifer varieties were bred from witches' brooms.

What was candy corn originally called when it was invented in the 1880s?

George Renninger of the Wunderle Candy Company created it. Goelitz, now Jelly Belly, started making it in 1898.

Which Gaelic harvest festival is thought to have influenced many Halloween traditions?

Halloween falls on 31 October, the eve of All Hallows' Day, and some think the Church Christianised Samhain into it.

What are the three most common specific phobias?

Between 8.7 and 18.1 per cent of Americans have a phobia, making it the most common mental illness among women.

In folklore, what is tied to a mandrake root to pull it up, since its scream kills?

The trick goes back to Josephus in the first century, who described sacrificing the animal to harvest a plant he called baaras.

What lets most owls fly almost without a sound?

A velvety surface on the feathers absorbs more noise. Fish-eating owls, which gain nothing from stealth, lack the adaptation.

Most stage fog machines make their haze by vaporising water mixed with what?

The hot vapour condenses into visible fog as it meets cooler air. Performers call the fluid 'fog juice'.

Egyptian embalmers dried a body for 70 days in which naturally occurring salt?

Herodotus insisted the timing mattered: shorter and the corpse was not fully dehydrated, longer and it was too stiff to pose for wrapping.

Renaissance Italian courtesans used deadly nightshade berry juice to do what?

Hence the plant's name Atropa belladonna, 'pretty woman'. Its alkaloid atropine is still dropped into eyes before examinations.

Vampire bats locate blood close to the skin with nose receptors that sense what?

The only other vertebrates with this sense are boas, pythons and pit vipers. The bats retune a heat channel, TRPV1, to fire at about 30°C.

When you crack a glow stick, what spills out of the inner glass vial?

It meets diphenyl oxalate and a dye in the outer tube. The reaction releases almost all its energy as light, barely any as heat.

The tarantula hawk's sting is second on the Schmidt pain index behind which insect?

Schmidt called the wasp's sting 'blinding, fierce, shockingly electric', though the worst of it passes in about five minutes. Roadrunners eat them anyway.

Scientists blame will-o'-the-wisp lights over marshes on methane igniting with which gas?

Phosphine and diphosphane from decaying matter ignite spontaneously in air, so a whiff is enough to light the far more plentiful marsh gas.

In which city did Giovanni Aldini electrically twitch a hanged man's corpse in 1803?

Galvani's nephew wired up the hanged murderer George Foster; onlookers reportedly thought the body was coming back to life, fifteen years before Frankenstein.