Appearance
12.3 — Animals and the Records They Hold
The record holders, the creatures with undeserved reputations, and the several famous animal facts that are simply false.
The extremes
What is the largest animal that has ever lived?
The blue whale, and it is not close.
Up to about 30 metres and 150 to 190 tonnes. Its tongue alone can weigh as much as an elephant; its heart weighs around 180 kilograms; a newborn calf is 7 metres long and gains around 90 kilograms a day on its mother's milk, which is roughly 40 per cent fat.
It is larger than any dinosaur. The largest sauropods were longer in some estimates but far lighter, because a land animal's mass is limited by what its legs can support. Water removes that constraint entirely, which is why the biggest animals in history are all marine.
Blue whales feed on krill, animals a few centimetres long, and eat up to 4 tonnes a day. The largest animal ever eats one of the smallest, which works because krill occur in swarms dense enough to filter.
They were hunted to around one per cent of their pre-whaling population by the mid-twentieth century and have recovered only partially since protection in 1966.
What are the other size records?
Largest land animal: the African bush elephant, up to about 6 tonnes. Tallest: the giraffe, up to 5.5 metres, whose neck contains seven vertebrae — the same number as yours, each enormously elongated. Longest: possibly the bootlace worm, a marine ribbon worm, with specimens claimed at over 50 metres, though the animal stretches and the measurements are unreliable. The lion's mane jellyfish reaches comparable lengths including tentacles. Smallest mammal: the bumblebee bat and the Etruscan shrew compete, both around 2 grams. Smallest vertebrate: a frog from Papua New Guinea, about 7.7 millimetres.
Largest ever flying animal: the pterosaur Quetzalcoatlus, with a wingspan around 10 to 11 metres — the height of a giraffe when standing on the ground. How it took off is still argued about.
Which animals live longest?
Longest confirmed for a vertebrate: the Greenland shark, with individuals radiocarbon-dated at around 270 to 400 years. They reach sexual maturity at about 150.
Ocean quahog, a clam, has been aged at 507 years by counting growth rings in its shell — and the specimen that established the record was killed in the process of aging it.
Bowhead whales exceed 200 years, established partly by finding nineteenth-century harpoon points embedded in living animals.
Tortoises routinely exceed 150. Jonathan, a Seychelles giant tortoise on Saint Helena, was estimated as hatched around 1832, which makes him the oldest known living land animal.
And Turritopsis dohrnii, a small jellyfish, can revert to an earlier life stage when stressed, potentially indefinitely — the basis of the "immortal jellyfish" description. It is a real and verified process; the animal can still be eaten or diseased, so immortality is theoretical rather than practical.
Which are the fastest?
Peregrine falcon, in a dive, above 380 km/h — the fastest animal of any kind. It has bony tubercles in its nostrils that manage airflow at that speed.
Fastest on land: the cheetah, around 100 to 120 km/h, sustainable for perhaps 30 seconds before overheating forces it to stop. The pronghorn antelope is slower at top speed and far better over distance, able to hold 55 km/h for kilometres — a speed with no living predator to justify it, and generally explained as a response to an American cheetah that went extinct 12,000 years ago.
Fastest in water: black marlin and sailfish, claimed above 100 km/h, though the measurements are contested.
Fastest movement of any kind belongs to small things. The mantis shrimp's strike accelerates at over 100,000 times gravity and moves so fast it boils the water in front of it — producing a collapsing bubble whose implosion generates a second shockwave, a flash of light and temperatures briefly comparable to the sun's surface. The prey is hit twice by one punch.
The toughest
What can a tardigrade actually survive?
More than almost anything, and the caveat is important.
In a dried, suspended state called a tun, tardigrades have survived temperatures from close to absolute zero to above 150 °C, pressures six times those at the bottom of the ocean, radiation doses hundreds of times lethal for a human, and ten days of direct exposure to the vacuum and radiation of open space, in a 2007 European Space Agency experiment.
They achieve it by replacing the water in their cells with sugars and specialised proteins that vitrify — set into a glass-like state — physically immobilising cell structures so they cannot be damaged.
An active, hydrated tardigrade is not tough at all. It is a half-millimetre animal that can be crushed by anything. The abilities belong to the dormant state, and the internet reputation consistently omits this.
Which animals survive without oxygen, food or water?
Kangaroo rats never drink. They obtain all their water metabolically — as a by-product of breaking down the food they eat — and their kidneys concentrate urine to an extraordinary degree.
Camels do not store water in their humps, which hold fat. Their tolerance comes from a body temperature that swings several degrees to avoid sweating, red blood cells that survive extreme dilution when they finally drink, and the ability to lose 25 per cent of body mass in water without collapse — a level that would kill most mammals at 15.
Henneguya salminicola, a parasite of salmon, was found in 2020 to have no mitochondrial genome at all, making it the first known animal that does not breathe oxygen.
Wood frogs freeze solid each winter — up to 65 per cent of their body water turns to ice, their heart stops, and they thaw in spring — protected by glucose acting as antifreeze in their cells.
Undeserved reputations
Which famous animal facts are false?
Goldfish do not have three-second memories. They can be trained to respond to signals, navigate mazes, and remember for months. The claim has no identifiable source.
Bats are not blind. All bats can see, and fruit bats have excellent vision. Echolocation supplements sight in the dark; it does not replace it.
Ostriches do not bury their heads in the sand. They lie flat with their necks on the ground to be less visible, and they turn eggs in a ground nest with their beaks, which from a distance looks like it.
Lemmings do not commit mass suicide. The belief was cemented by a 1958 Disney documentary in which the filmmakers drove the animals off a cliff with a rotating turntable and filmed the result.
Bulls are not enraged by red. Cattle are dichromats and cannot distinguish red as humans do. The bull charges the movement of the cape; the colour is for the audience.
Touching a baby bird does not make its mother reject it. Most birds have a poor sense of smell and will not abandon a chick. The advice is still good, for other reasons.
An elephant does not fear a mouse in any tested way, and a duck's quack does echo — a claim tested at the University of Salford, which found the echo is real and just hard to notice because a quack fades gradually.
And a swallowed piece of chewing gum does not stay in you for seven years. It passes through in a few days like anything indigestible.
Which animals are more dangerous than their reputation, and which less?
Sharks kill fewer than ten people a year worldwide. Cows kill more. Vending machines have historically killed a comparable number.
The deadliest animal to humans by a very wide margin is the mosquito, through malaria, dengue, yellow fever and others — a death toll in the hundreds of thousands annually. Second is the human being. Third, in most counts, is the snake, at 80,000 to 140,000 deaths a year, the majority in South Asia and sub-Saharan Africa.
Hippos kill several hundred people a year in Africa and are extremely aggressive despite being herbivores.
And the box jellyfish carries one of the most potent venoms known, capable of killing a human in minutes.
Going the other way: wolves attack humans very rarely; spiders in most of the world are medically insignificant; and bats, despite the rabies association, are a minor cause of human harm relative to their enormous ecological value in pest control and pollination.
The strange ones
Which animals do something genuinely bizarre?
The octopus has three hearts, blue copper-based blood, and around two thirds of its neurons in its arms rather than its brain, so each arm carries out substantial processing independently. It can taste with its skin and solve novel problems, and it lives about one to two years.
The mantis shrimp has up to sixteen photoreceptor types against the human three. The popular claim that it therefore sees an unimaginable range of colours turned out to be wrong: behavioural testing in 2014 found it discriminates colours worse than humans do. It appears to use its many receptors to identify colour quickly without comparing them, which is a different trade-off, better suited to fast reactions than to fine discrimination.
The axolotl regenerates limbs, jaw, spinal cord and parts of its heart and brain, and remains in its larval form for life while still becoming sexually mature. It is critically endangered in the wild, surviving in a small area of canals near Mexico City, while being one of the most abundant laboratory animals in the world.
The platypus lays eggs, produces milk without nipples by sweating it through the skin, has venomous spurs on the males' hind legs, and hunts with electroreception through its bill with its eyes and ears closed. The first specimen sent to Britain was assumed to be a hoax stitched together from other animals.
Naked mole rats live in eusocial colonies with a single breeding queen, like ants; feel no pain from acid or capsaicin; show almost no increase in death rate with age; and are extraordinarily resistant to cancer. They survive in low-oxygen conditions by switching to fructose metabolism, which no other mammal does.
Sea otters hold hands while sleeping so they do not drift apart, and use stones as tools, keeping a favourite one in a pouch of loose skin under the arm.
Which animal intelligences are underestimated?
Corvids — crows, ravens, jays — make and use tools, plan for future needs, recognise individual human faces for years, and hold what appear to be grudges. New Caledonian crows manufacture hooked tools from twigs, and one, in a laboratory, solved an eight-step puzzle requiring tools to obtain tools.
Pigs outperform dogs on several problem-solving measures and can be trained to use a joystick-operated screen.
Cephalopods are covered above, and their intelligence is remarkable partly because it evolved on a completely separate branch — the last common ancestor of a human and an octopus was something like a flatworm around 600 million years ago. It is the closest thing available to studying an intelligence that arose independently.
Elephants recognise themselves in mirrors, use tools, appear to mourn their dead, and communicate over kilometres using infrasound below human hearing, partly through the ground.
Cleaner wrasse, a small fish, passed a mirror self-recognition test in 2019 — a result that has forced a genuine argument about whether the test measures what it was assumed to measure.
What comes next
The next page decodes the labels people wear rather than the animals — what a PhD actually is, what the job titles mean, and where honours and certifications come from.