Odd truths about animals
Creatures quietly breaking rules you assumed were rules.
Do octopuses really have three hearts?
Yes. An octopus has three hearts: two branchial hearts that push blood through the gills, and one systemic heart that sends it around the body. The systemic heart stops beating when the octopus swims, which is part of why they would rather walk.
Why is wombat poop cube-shaped?
Because their intestines are not uniformly stiff. Research published in Soft Matter found regions of the wombat's gut are twice as thick and four times as stiff as neighbouring regions, so contractions mould corners into the faeces over the final stretch of intestine.
Are sharks older than trees?
Yes. Sharks appear in the fossil record around 450 million years ago; the first true trees show up around 385 million years ago. Sharks predate forests by roughly 65 million years — about the same gap that separates us from the last dinosaurs.
How hard does a mantis shrimp punch?
Fast enough to boil water. A 2004 Nature study clocked the peacock mantis shrimp's club at around 23 metres per second, accelerating like a bullet. The strike drops the water pressure so sharply that vapour bubbles form and violently collapse — so prey gets hit twice.
Can turtles really breathe through their butts?
Some can. Several freshwater turtles absorb oxygen through the lining of the cloaca. The Fitzroy River turtle of Australia does it well enough to meet effectively all of its oxygen needs this way, letting it stay submerged for extraordinarily long stretches.
Do sea otters hold hands while they sleep?
Sometimes, genuinely. Resting sea otters do link paws so they don't drift apart from their raft. It is real behaviour and not a myth — but it is less frequent than the internet implies, and rafts mostly stay together by watching and listening to each other.
Can bees recognise human faces?
Yes. In a 2005 study, honeybees were trained on photographs from a standard human face-recognition test and picked the target face out from a similar distractor with better than 80 percent accuracy — and still remembered it two days later.
Have tardigrades survived in open space?
Yes. In 2007 the European Space Agency exposed dried tardigrades to the vacuum of low Earth orbit for ten days. Those shielded from solar UV revived at rates comparable to controls on the ground, and went on to lay eggs that hatched normally.
Can sloths hold their breath longer than dolphins?
Yes. Sloths can stay underwater for up to about 40 minutes by slowing their heart rate dramatically. Most dolphins manage roughly 10 to 15 minutes. The animal built for water loses to the animal built for hanging in a tree.
Do any birds have contagious laughter?
Yes. New Zealand's kea has a distinct play call, and researchers found that simply playing a recording of it puts other kea in the mood to play. It is the first known case of emotionally contagious vocalisation in a non-mammal.
Can a cockroach live without its head?
Yes, for a week or more, and in lab conditions for several weeks. Cockroaches breathe through holes along their body rather than through their mouth, their blood does not need high pressure so the neck seals by clotting, and simple nerve clusters in each segment keep the legs working. A headless roach eventually dies of thirst, not of losing its head.
Do crows remember human faces?
Yes, for years. University of Washington researchers trapped crows while wearing a rubber mask, then found that for years afterwards crows across campus scolded anyone wearing that mask, even crows that had never been caught and crows hatched after the experiment. They recognise individual faces and pass the warning on.
Do dolphins have names for each other?
Yes. Each bottlenose dolphin invents its own signature whistle early in life, and a 2013 study from the University of St Andrews showed that wild dolphins respond when they hear a copy of their own whistle and ignore copies of other dolphins'. It is the closest thing to a name found in any animal other than us.
Do butterflies taste with their feet?
Yes. Butterflies have chemical sensors on their feet, so when one lands on a leaf or a flower it is tasting it. Females use this to check a plant is the right kind before laying eggs on it, since most caterpillars can only eat a few specific plants.
Why are flamingos pink?
Because of their food. Flamingos hatch with white or grey down and turn pink over several years as pigments from the algae and tiny shrimp they eat build up in their feathers. A flamingo on a different diet would slowly fade.