Some interesting Facts

You shouldn’t believe everything you read on the internet. For example, there are plenty of pages that solemnly tell you flamingoes bend their knees backwards. In fact, all birds have forward-facing knees: the knee is up in their feathers, the ankle is the bit that goes backwards, their foot bones are fused together, and birds walk on their toes. This is because birds are dinosaurs: T. rex walked the same way, but his foot bones weren’t fused yet. Isn’t the real story usually more interesting?

This is my personal collection of strange but true zoological trivia. Why should you believe me when I say it's true? Good question. All these facts were taken from original research by scientists, and as I work on this page I’ll be adding references so if you wanted you could go check. Until then I can supply references if you e-mail me. Don’t take my word for anything. Nullius in verba. That’s why science works.

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Campbell, Kenneth E., and Eduardo Tonni (1983). Auk 100:390–403.

The biggest flying bird that ever lived, back in the Miocene (million years ago) was called Argentavis. It was the size of a small plane. The biggest bird ever was either the Elephant Bird of Madagascar (Aepyornis) or the Giant Mihirung of Australia (Dromornis), depending on whether you’re talking to Australians or not. Personally I think the biggest bird was a giant unnamed penguin that, by my calculations, stood 5 feet 9 inches tall (175 cm) and weighed over 300 kg (about 700 lb).

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Henderson and Walker (1990). Journal of Fish Biology 37:401–411

There’s a wormlike parasitic catfish in the Amazon that lives entirely out of the water, slithering around in piles of leaves on the bank. It breathes through its skin, and is bright red and blind.

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Before human beings arrived, North America looked a little like the African savanna, with elephants, horses, camels, antelope, bison, cheetahs, tapirs, jaguars, lions, giant tortoises, and even giant beavers. Why are only bison and antelope left? Well, it’s possible the others all dropped dead coincidentally just after humans arrived. It’s possible that the conservation-minded indigenous Americans didn’t eat them all. But that would be the first and last time ever that humans didn’t wipe out everything they could as quickly as they could. Perhaps North America is just super special.

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Grützner, Frank et al (2004). Nature 432, 913–917.

The duck-billed platypus is weird enough for a whole web page. Sure, it has a ducklike bill. Boring. But it can sense electrical fields through tiny pits in the bill, and uses it to hunt under stones in rivers. It lays eggs, and feeds its young by sweating (lactose-free!) milk through its belly fur. Male have venomous spurs on their hind legs. And, weirdest of all, the platypus has ten sex chromosomes; that is, males are XYXYXYXYXY and females XXXXXXXXXX. Nobody knows why.

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Nakata, S. and Maa, T.C. (1974). Pacific Insects 16:307–374

The naked bulldog bats (two species of Cheiromeles) live in Southeast Asia. They have thick dark skin, with just a few bristles they use for grooming. They fold their wings into side pockets so they can run around on four legs on the forest floor. And crawling all over them are parasitic earwigs—nearly-blind, giant, flightless, hairy earwigs (Arixenia esau, after the biblical hairy man).

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Your skin makes up 15% of your body weight.

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All hail the tuatara (Sphenodon) of New Zealand! It has a third eye in the middle of its head! It’s not a lizard, but the last representative of the 225-million-year old Rhynchocephalia! It has the lowest body temperature of any reptile and sits motionless for days at a time! It can hold its breath for an hour (or possibly it just forgets to breathe)! In captivity it’s indistinguishable from a well-painted rubber model of a tuatara! It has two rows of teeth in its upper jaw, and chomps down like a mofo! It can live for over 100 years! It does’t have a penis! It’s endangered!

Disclaimer: Third eye is microscopic and present briefly in hatchlings. Third eye presented for informational purposes only and tuatara assume no responsibility for functionality or visibility, stated or implied.

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Owls can rotate their heads 270°. How do they do it? Their neck vertebrae are very short and close together, and while each one can twist about as much as ours can, they have twice as many as we do.

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Most mammal lives contain roughly same number of heartbeats: about 946 million. A mouse heart beats about 600 times a minute, but an elephant’s only 30 times, so elephants tend to live a lot longer than mice—about 60 years, in fact. (Whale hearts only beat nine times a minute, so they mess up the equation a bit; they don’t live that much longer than elephants. We don’t fit the model either, reaching 946 million beats before we’re 30. Strangely, anteaters also don’t fit. Who knows why.)

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Smaller dogs live longer (short people do too, but that’s another story). For every kilogram one dog breed is heavier than another, it loses 18 days of life expectancy.

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Elephant shrews give birth to amazingly advanced young: their mothers provide milk for less than a day, then they’re on their own. Kiwi (Apteryx) chicks are also pretty independent. They carry so much remnant egg yolk inside themselves that they don’t need to eat for their first two weeks, and after that they can forage by themselves.

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Most of the ocean’s biomass is made up of viruses.

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The world’s smallest bat is Kitti’s Hog-Nosed Bat (Craseonycteris thonglongyai), more commonly known as the bumblebee bat. It’s found only in a few caves in western Thailand, is about 30 mm long (that’s 1.2 inches), and weighs around 2 g (0.07 oz), less than a dime. The Etruscan Pygmy Shrew (Suncus etruscus) might weigh a little less. Which is the world’s smallest mammal? I think they should duke it out, which might not be decisive but would, you have to admit, be very cute.