47 Fun Facts About Halloween Science

Bats are the only mammals capable of what?

Powered flight is the bats' alone: flying squirrels, despite the name, can only glide from tree to tree, while a bat flaps a wing built from its own hand, with skin stretched between long fingers.

Bats are the second-largest order of mammals, with more than 1,400 species, behind only which group?

Rodents make up about 40% of all mammal species and bats about another 20%, so more than half of the world's mammals are one or the other.

Of more than 1,400 bat species, how many feed only on blood?

Three: the common, hairy-legged and white-winged vampire bats, all in Latin America. A vampire that fails to feed can beg from a roost-mate, which brings up part of its own blood meal to keep it alive.

What is draculin, found in vampire bat saliva?

An anticoagulant: draculin blocks two of the blood's clotting factors, so the small bite keeps flowing while the bat laps up its meal.

Spiders, scorpions and ticks all belong to which class of animals?

Arachnids. A spider straightens its legs not with muscle but by pumping fluid into them like a hydraulic ram, which is why the legs fold inward when the pressure goes.

Weight for weight, spider silk is stronger than steel but weaker than which material?

Kevlar is stronger still, but it is stiff where silk stretches, so a web can soak up the energy of a flying insect without snapping.

Spider web threads found in amber from Sussex, England, date from the age of which animals?

Dinosaurs: the amber is about 140 million years old, and its threads already carry sticky droplets, so spiders were gluing down their prey the way garden orb weavers do today.

Many New World tarantulas defend themselves by kicking what off their abdomens at an attacker?

Barbed hairs: the barbs let a bristle work its way into skin and eyes, and doctors have had to remove them surgically from the eyes of people handling pet tarantulas.

A pumpkin is a cultivated variety of which kind of plant?

Winter squash is picked fully ripe, once the rind has hardened, which is why a pumpkin will keep through the winter while a summer squash such as a courgette is eaten young and tender.

How heavy was the pumpkin that set a world record in October 2023?

About 1,250 kg: Travis Gienger's pumpkin weighed 1,246.9 kg. It held the record until 2025, when English twins who had been growing giants for 50 years beat it by 32 kg.

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

Turnips and mangelwurzels were hollowed out as lanterns, and Irish legend has Stingy Jack roaming the earth with a coal in a carved turnip. Immigrants to America switched to the native pumpkin.

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

Strange lights flickering over peat bogs were pictured as a man carrying a lamp, 'Jack with the lantern', who was said to lead night travellers astray. The name reached carved pumpkins only in the 1800s.

Which pigment gives a pumpkin its orange colour and is turned into vitamin A by the body?

Beta-carotene also colours carrots and sweet potatoes, and eating a great deal of them can tint your palms and soles orange-yellow, a harmless effect that fades when you cut back.

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

Melanism also makes the 'black panther', which is no species of its own, just a black leopard or jaguar. The trait has arisen separately in cats: one mutation blackens a house cat, a different one a jaguar.

Which American physiologist first described the 'fight or flight' response?

Walter Cannon was X-raying animals' stomachs to watch digestion when he noticed the movements stopped whenever the animal was upset, and he followed that clue to the body's emergency response.

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

The amygdala was destroyed by a rare disease in an American woman known as S.M. Researchers who walked her through a haunted house and showed her horror films found they could not frighten her.

Rather than pitch or volume, which sound quality, a rapid flutter in loudness, did a 2015 study find makes screams alarming?

Roughness, loudness that flickers 30 to 150 times a second, sets a scream apart from speech and is also built into artificial alarms; it engages the brain structures that size up danger.

Goosebumps form when a tiny muscle tightens at the base of each what?

Hair: each one has its own muscle, the arrector pili, that pulls it upright. In our furry ancestors that trapped warm air or made a frightened animal look bigger; on bare skin it leaves only bumps.

The glands that make adrenaline sit on top of which organs?

The kidneys: 'adrenal' comes from the Latin for 'near the kidney', and each of the two small glands sits like a cap on top of one.

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

Carbon dioxide never melts at everyday pressure: the solid turns straight into gas. Dropped in water, it throws up white 'smoke' that is really a fog of tiny water droplets, chilled so that it hugs the floor instead of rising.

Dry ice turns straight from a solid into a gas, a change known as what?

Sublimation happens at -78.5°C in dry ice, cold enough to burn bare skin like frostbite, which is why it is handled with insulated gloves.

What kind of reaction makes a glow stick glow?

Chemiluminescence turns a reaction's energy straight into light with almost no heat, which is why a glow stick stays cool in the hand: the same cold glow lights a firefly.

Which enzyme makes a firefly's tail light up?

Luciferase makes the light by oxidising a compound called luciferin. Female Photuris fireflies copy another species' flash code to lure in its males, then eat them.

Owls turn their heads so far because they cannot do what?

Move their eyes: an owl's eyes are tubes held fast in the skull, so the whole head turns instead, up to 270 degrees each way, and holes in the neck bones ten times wider than the artery inside keep blood flowing.

An owl has 14 neck bones, twice as many as which animal?

The giraffe has only seven neck bones, the same number as a human: each one is simply stretched, to more than 25 cm.

Which video game and TV series took its brain-hijacking infection from the real 'zombie-ant fungus'?

The Last of Us imagines the fungus jumping to people. In real carpenter ants it drives the insect down from its nest to clamp its jaws on a leaf vein and die, and a stalk then sprouts from its head to shed spores.

Toxoplasma gondii changes the behaviour of infected mice and rats so they are more likely to be eaten by which animals?

Cats are the only animals in which the parasite can reproduce sexually, so it rewires infected mice and rats to be drawn to the smell of cat urine instead of fleeing it.

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

Carrion beetles and flies come looking for a carcass to lay their eggs in and carry off pollen instead. The bloom even heats itself to about 36°C, in pulses, to drive the stench further.

Chocolate is toxic to dogs because of which compound?

Theobromine lingers in a dog, which needs about 17.5 hours to clear half a dose, so the stimulant builds up to a poisonous level. Dark and baking chocolate carry the most.

How many bones are in an adult human skeleton?

206 is what is left after years of fusing: a baby is born with dozens more bones, and pieces such as the five vertebrae at the base of the spine knit into one as the body grows.

Rigor mortis sets in because muscle fibres need a supply of energy in order to do what?

Relax: a muscle fibre needs fresh ATP to let go of its grip, so when the supply runs out after death the fibres lock solid. They loosen again only when decay starts to break them down.

In which decomposition stage do maggots strip the most mass?

Active decay is the third of five stages, after fresh and bloat. Maggots feed so hard that the body loses more mass than in any other stage, and their size tells investigators the least time that can have passed since death.

The old belief that the full moon drives people mad gave English which word for insanity?

Lunacy comes from the Latin luna, moon, but the belief has not survived testing: reviews pooling dozens of studies of crime, births and hospital admissions find no link with the moon's phase.

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

Hypertrichosis ran in the family of the 16th-century courtier Petrus Gonsalvus: portraits of him and his children hang in Ambras Castle in Austria, which gave the condition another of its names, Ambras syndrome.

What do foresters call a dense mass of shoots growing from a single point on a branch?

Witch's broom can be the work of an invader: on birches a fungus infects the buds, which sprout a dense bunch of stunted twigs that can last for years.

Which Gaelic festival, marking the end of the harvest, is thought to have shaped many Halloween traditions?

Samhain was when the barrier with the Otherworld was thought to fall: families left out food and drink for visiting spirits, and people went door to door in costume, reciting verses in return for food.

What are the three most common specific phobias?

Fear of spiders, snakes and heights far outruns fear of sockets or hammers, which hurt more people today. Psychologists argue that evolution primed us to learn fears of ancient dangers fastest.

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

A dog was tied to the root and, straining to follow its master as he left, pulled the plant free and died in his place. The first-century historian Josephus describes the trick for a root he calls baaras.

What lets most owls fly almost without a sound?

Serrated edges on wing feathers break up the rushing air, and a velvety surface soaks up more of the sound. Pel's fishing owl, whose prey cannot hear it coming, has lost the soft feather edges.

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

Glycol or glycerin is heated with water until it turns to vapour, then condenses into a thick white mist as it meets the cooler air. The same two liquids make the clouds from an e-cigarette.

Egyptian embalmers packed a body in natron to do what?

Dry it out: natron, a salt gathered from desert lake beds, draws the water from flesh before decay can take hold. It also gave sodium its chemical symbol, Na.

Renaissance Italian women are said to have widened their pupils with the juice of which poisonous plant?

Deadly nightshade is Atropa belladonna, and the Italian for 'fair lady' is commonly put down to that fashion. Its drug atropine is still used in eye drops to widen the pupil.

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

Infrared heat is read by pits around the bat's nose: it retuned a sensor that normally warns of scalding temperatures so that it fires at about 30°C. Among animals with backbones, only boas, pythons and pit vipers share the sense.

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

Hydrogen peroxide floods out to meet an oxalate ester and a dye in the outer tube. Warmth speeds the reaction, so a stick glows brighter in hot water and lasts longer if it is chilled.

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

Bullet ant stings burn for up to 24 hours, while the wasp's 'blinding, fierce, shockingly electric' jolt is over in about five minutes. Even so, the roadrunner is one of the few animals that will eat one.

Will-o'-the-wisps have long been blamed on which gas that bubbles up from rotting marsh plants?

Methane was the suspect for centuries, but nobody could prove what lit it. In 2025 chemists filmed tiny sparks, which they called microlightning, jumping between rising bubbles of the gas and setting off a faint glow.

Giovanni Aldini, who electrified a hanged man's corpse in 1803, was which scientist's nephew?

Luigi Galvani had made dead frogs' legs kick with a spark. His nephew scaled the show up, and when the dead man's jaw quivered and one eye opened, some onlookers thought he was coming back to life.