Creatures of the Night – answers and explanations
Here are the answers to all 15 questions in the Creatures of the Night quiz, each with a short explanation. Bats, owls, spiders and wolves: the real animals behind Halloween's spookiest symbols. Haven't played yet? Take the quiz first and compare your score.
Play the quiz · 15 questions1. What is the anticoagulant found in vampire bat saliva aptly named?
Answer: Draculin
Draculin is a glycoprotein isolated from the saliva of the common vampire bat (Desmodus rotundus); named in a 1995 paper, it blocks clotting factors IXa and Xa so the victim's blood keeps flowing while the bat feeds.
2. Which wing feature lets owls fly almost silently towards their prey?
Answer: Comb-like fringes along the feather edges
Owls fly almost silently thanks to a comb of serrations on the leading edge of the outer wing feathers, plus a soft fringe at the trailing edge and velvety feather surfaces. These three features were described by aeronautical engineer Robert Rule Graham in 1934.
3. Scorpions produce a striking reaction when placed under which kind of light?
Answer: Ultraviolet light, under which they glow blue-green
Nearly all scorpions fluoresce bright blue-green under ultraviolet light because compounds such as beta-carboline in the hyaline layer of their cuticle absorb UV and re-emit it as visible light. Researchers use UV torches to survey scorpions at night.
4. Legend says the British crown will fall if ravens ever leave which building?
Answer: The Tower of London
Tradition says the Tower of London and the kingdom will fall if its resident ravens ever leave, so at least six ravens are kept there, cared for by a Yeoman Warder known as the Ravenmaster. The custom is popularly credited to Charles II.
5. What do scientists think moths use as a steering reference on night flights?
Answer: The steady light of the moon
The leading explanation for night-flying moths' orientation is transverse orientation: they hold a fixed angle to a distant light such as the moon to fly straight. Close artificial lights break the trick, making moths spiral in towards the bulb.
6. Vampire bats locate blood vessels using heat sensors found on which body part?
Answer: The nose
Common vampire bats have three heat-sensing 'leaf pits' around the nose-leaf that detect infrared radiation, helping them find blood-rich spots on warm-blooded prey. A 2011 Nature study showed this works via a modified TRPV1 channel that fires at about 30C.
7. Why does an owl swivel its whole head instead of just glancing sideways?
Answer: Its tube-shaped eyes are fixed in their sockets
Owl eyes are elongated tubes locked in place by bony sclerotic rings, so they cannot roll in their sockets and the bird must turn its head to look around. With 14 neck vertebrae, twice the human count, owls can rotate the head roughly 270 degrees.
8. How does a spider usually avoid getting stuck in its own web?
Answer: It walks on the non-sticky spoke threads
In an orb web, only the spiral capture threads carry glue droplets, while the radial spokes and frame are dry, so the spider travels mainly on those safe lines. Careful leg movements and non-stick hairs on the feet give extra protection when it must touch sticky silk.
9. In traditional British folklore, a black cat crossing your path means what?
Answer: Good luck is coming
In Britain a black cat crossing your path is traditionally a sign of good fortune, the opposite of the American and much of continental European belief. British sailors and their families also kept black cats as lucky charms for safe voyages.
10. What is the main purpose of a wolf pack's long night-time howling?
Answer: Keeping pack members in contact over long distances
Howling is a long-distance contact call that lets scattered pack members locate and rejoin each other, carrying up to about 10 miles over open terrain. It also advertises a pack's presence to rivals, but it is sound, not scent, and has nothing to do with the moon.
11. Some moths escape hunting bats by emitting what to scramble the bats' sonar?
Answer: Ultrasonic clicks
Some tiger moths answer an attacking bat with rapid bursts of ultrasonic clicks that jam its echolocation. A 2009 Science study by Corcoran, Barber and Conner showed Bertholdia trigona clicking up to about 4,500 times a second, letting it escape big brown bats.
12. What do well-fed vampire bats often do for a hungry roost mate?
Answer: Regurgitate part of their blood meal
Common vampire bats that have fed will regurgitate part of their blood meal into the mouth of a roost mate that failed to feed, since the bats can starve after only a few nights without blood. Gerald Wilkinson's work made this a textbook case of reciprocal altruism.
13. Which reflective eye layer makes a cat's eyes glow in the dark?
Answer: Tapetum lucidum
The tapetum lucidum is a mirror-like layer behind the retina that bounces light back through the photoreceptors, boosting night vision and causing eyeshine. Cats, dogs and many nocturnal hunters have it; humans do not.
14. In traditional Japanese folklore, a black cat is believed to bring what?
Answer: Good luck
In Japan black cats are regarded as lucky rather than ominous, and are linked to the beckoning maneki-neko figurine. Black versions were used as charms against evil spirits and illness, a belief popularised during the Edo period.
15. What can crows recognise so well that they hold grudges for years?
Answer: Individual human faces
American crows can recognise individual human faces and keep scolding people who once threatened them. In John Marzluff's University of Washington mask experiments begun in 2006, crows mobbed the 'dangerous' caveman mask for years and even taught other crows to do so.