SUPERPOWER #1 Colossal Orbs of Telescopic Vision HERE'S AN INTERESTING FACT: birds have far, far better vision than we do, or than any other mammal does. Birds can see colors we can't even imagine. They see movements that are too fast for our eyes to notice. Their left and right eyes can see different things at the same time! Even scientists don't yet understand all the amazingness of bird eyeballs. Part of the reason birds see so much better is they have huge eyes. An eagle or an owl is less than a third of your size but has eyeballs as big as yours. And Eno? Well, Eno has the biggest eyeballs of any animal on land. Let me say that again: ENO HAS THE BIGGEST EYEBALLS OF ANY ANIMAL ON LAND. His eyeballs are bigger than a giraffe's or even an elephant's! Only sea giants like whales and colossal squids have bigger eyes. Bigger eyes mean better vision. But before I explain why, do you understand how eyeballs work? Eyeballs are amazing and intricate and very complicated. But an eyeball is basically just a ball of jelly with a hole at the front and a screen at the back. Light goes in the hole and shows an image of the outside world on the screen. Then special light-gathering information bits inside the screen send all the information about that image to your brain. As you probably know with televisions, a bigger screen usually has a better image. A giant television screen has so many more pixels--or dots of color and detail--than the teeny TV in your granny's kitchen, which means a giant screen would show your granny's cooking shows in way more detail, if she ever bought a new TV. The same goes for eyes. The huge screens at the back of Eno's colossal eyeballs have way, way more light-gathering information bits than the small screens in your eyes, which means Eno sees the world in much, much clearer detail than you do. Eno's eyes can spot the slightest twitch of grass that our eyeballs wouldn't notice. That might give him a split-second head start that could save his life. And more of those light-gathering information bits also means Eno sees much better in dimmer light at dusk when lions like to hunt. Now, your teacher will be angry if I don't tell you the proper words for your eyeball parts. So, the hole at the front is called a pupil. The screen at the back is a retina. The jelly is called vitreous humor --it looks like colorless hair gel. And the light-gathering information bits are called photoreceptors. There are different kinds of photoreceptors that do different things, but we don't need to worry about that right now. Bird eyes also have something yours don't--a strange comb-like lump filled with blood vessels. It's inside their eyeball, and it's called a pecten or a pecten oculi, if you want to be fancy. Scientists don't understand all the amazing things it does, but they know it nourishes the retina. And that means the retina needs fewer blood vessels, so there is room in the retina for even more photoreceptors, for even sharper bird vision. Wow! Next, Eno's eyeballs are shaped differently than yours. Your eyeball is rounder at the back, which means the image quickly gets blurry as the retina curves around the sides of your eyeball. But ostrich eyes are flatter at the back, which means the retina is flatter, which means more of the image is in focus, especially at the sides. And that means Eno could read this book just as well if you held it at the side of his head as if you held it straight in front of him. Hmm . . . ignore that last thing I said. It's a bad example, and not only because Eno can't read. Eno's eyeballs are on the sides of his head--not at the front like yours--so his sideways vision is excellent. (Scientists call sideways vision peripheral vision .) In fact, because his eyes are on the sides, if you held this book right in front of Eno, he might not be able to see it at all. Ostriches can't see their own beaks! They can't even see what they are pecking at the moment they're pecking it! Crazy! But ostriches can see almost all the way around their heads, which is incredibly helpful when you're always on the lookout for predators. And this is still just the beginning of what makes Eno's eyeballs amazing. Ostriches also have . . . Look at it go! And look at the gazelles running. That cheetah only needed to twitch and the gazelles were off like lightning, darting and dashing in every direction. PHEW! The gazelles escaped, this time. A few seconds of high-speed action, then back to the peaceful savanna. It's so hot here, nobody wants to run for long. But that cheetah looks hungry. I think we should go before the sun sets, don't you? ENO IS ONE OF A KIND . . . AND KIND OF WEIRD THE SAVANNA HAS VARIOUS BIG CATS, like lions, cheetahs, and leopards. There are lots and lots of animals with hooves, like zebras, gazelles, giraffes, and wildebeests. There are doggy creatures, like African wild dogs and hyenas, which aren't dogs but sort of look like them. But there is only one giant bird on the savanna. Eno is one of a kind. Another way of saying "one of a kind" is "kind of weird." Even I can't argue that ostriches are a strange combination of bits: supersize chicken body, snaky neck, bobble head, no-fly wings, horse legs, horrible toes--and those are just the parts you can see. But "one of a kind" can also mean "AMAZING! STUPENDOUS! WHIZ-BANG-WOW!" And believe me, with all his weird bits working together, Eno is the fiercest, fastest warrior on the savanna. There is a lot to explain, so let's hurry up and meet the family! ENO'S FAMILY HERE'S UMA. BUT LET'S NOT BOTHER HER --she's sitting on her eggs. She might have as many as twenty eggs under there. Her grayish-brownish feathers really blend in with the dry savanna grasses, don't they? Eno has other girlfriends (ostriches usually live in smallish herds of a dozen or less), and some of them have laid eggs in the nest, but Uma is his main squeeze. If any of those eggs hatch, it will be Eno and Uma who raise the chicks, no matter who laid them. Ostriches belong to a strange group of flightless birds called ratites. Most are big and fierce, but none are as big and fierce as ostriches. Rheas and emus look a bit like Uma, but smaller and shaggier, with stumpy legs. Cassowaries look like giant prehistoric turkeys with dinosaur-tooth hats. And then you have the kiwis, which are only chicken-size and very shy. Not so long ago, much bigger ratites existed. New Zealand had giant moas that were thirteen feet (4 meters) tall! They were hunted to extinction shortly after humans first arrived on the islands, around 600 to 800 years ago. And Madagascar had elephant birds, the biggest birds ever. They were a little shorter than moas but heavier--they weighed as much as grizzly bears! They went extinct over two centuries ago, maybe because humans couldn't stop eating their eggs--each one was as large as 200 chicken eggs. And then, if you want to keep going back in time, we get to the dinosaurs. Eno isn't directly descended from Tyrannosaurus rex--they are more like ancient cousins. But Eno, T. rex, Velociraptor, and all the fiercest meat-eaters of the dinosaur world are part of the same family tree. They are all theropods, which means "beast-footed." (See! I told you Eno had horrible feet.) Sure, they are millions and millions and millions of years apart, but Eno is way more closely related to T. rex than he is to you or a cow. To be honest, all birds are theropods, which means all birds are living dinosaurs of sorts. But of all the birds I know, none look more like dinosaurs than ostriches. Next, I've told you Eno is big, but how big is he, REALLY? ENO IS REALLY BIG YOU MIGHT KNOW OSTRICHES are the biggest birds alive, but did you know that male ostriches like Eno can be over nine feet (2.7 meters) tall? Enormous! And Eno also weighs a lot. Most birds fly, so they need to stay light. But not ostriches. Eno weighs close to 320 pounds (145 kilograms). Massive! So ostriches are tall, and ostriches are heavy. But it's important to know which parts are tall and which parts are heavy, because they are not the same. Eno's neck is almost three and a half feet (1 meter) tall. Only giraffes have taller necks! But Eno's neck is super skinny and doesn't weigh much at all. Eno's legs are also super tall and skinny--they don't weigh much either. But do you know what isn't super tall and skinny? Eno's thighs. It's a bit hard to see under his wings, but each thigh weighs about 70 pounds (32 kilograms). Times two! Which means almost half of Eno's weight is in his thighs--that's 140 pounds (64 kilograms) of pure, raw, thundering thigh muscles! Those aren't just thighs. Those are THIGHS OF THUNDER! Excerpted from Ostriches by Rachel Poliquin All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
