Read this article in 4 levels: Basic A1 (英検3級), Intermediate B1(英検2級), Advanced C1(英検1級), original version. Multiple choice content questions for each level. Free English reading practice. The more you read in English, the more your English will improve. Why can owls turn their heads so far?
A1 Beginner 英検3級
B1 Intermediate 英検2級
C1 Advanced 英検1級
Original article
Basic A1 (英検3級) Version:
Article:
Why can owls turn their heads so far? It’s because their heads are connected by just one joint that can rotate a lot.
Owls are famous for turning their heads far around to see what’s behind them. This helps them stay safe and find food. Owls can turn their heads 270˚, which means they can look to the left and keep going until they are looking over their right shoulder. But they cannot turn their heads all the way around in a full circle. Most people can only turn their heads about 160˚.
Owls need to turn their heads so much because they cannot move their eyes. When we want to look behind us, we just move our eyes without turning our whole head. But owls have special eyes that are long and shaped like a cone, not round like ours. These eyes cannot move, so owls have to turn their heads instead.
There are two big differences between the necks of humans and owls. First, our heads connect to our spine with two bones, while owls have only one. This makes the owl’s neck much more flexible. Second, owls have more blood vessels in their necks than we do. When they turn their heads, the blood can still flow to their brains because there are many paths for the blood to take. This helps them stay safe while turning their heads.
Questions:
- Why can owls turn their heads so far?
a) Because they have big eyes
b) Because their necks are very flexible
c) Because they have long necks
d) Because they have round heads - How far can an owl turn its head?
a) 180˚
b) 270˚
c) 360˚
d) 90˚ - Why do owls need to turn their heads so much?
a) They cannot move their eyes
b) They have very small eyes
c) They have no necks
d) They want to scare other animals - How are owl’s eyes different from human eyes?
a) They are round
b) They are shaped like cones and cannot move
c) They are smaller
d) They are not used at night - How many bones connect a human’s head to their spine?
a) One
b) Two
c) Three
d) Four - What helps owls keep blood flowing to their brains when they turn their heads?
a) Big wings
b) More blood vessels in their necks
c) Stronger bones
d) Smaller heads - Why can’t humans turn their heads as far as owls?
a) Our necks are too short
b) Our blood vessels would get pinched
c) Our heads are too heavy
d) We have too many bones - What happens if an owl turns its head and one blood vessel gets pinched?
a) The owl gets dizzy
b) The blood flows through another vessel
c) The owl cannot see
d) The owl falls asleep - What part of the owl’s eye lets in light?
a) The cornea
b) The pupil
c) The retina
d) The eyelid - What is the main reason owls can turn their heads so far?
a) They are very strong
b) They have special necks and blood vessels
c) They are very light
d) They have big wings
Answers:
- b) Because their necks are very flexible
- b) 270˚
- a) They cannot move their eyes
- b) They are shaped like cones and cannot move
- b) Two
- b) More blood vessels in their necks
- b) Our blood vessels would get pinched
- b) The blood flows through another vessel
- a) The cornea
- b) They have special necks and blood vessels
Intermediate B1 (英検2級) Version:
Article:
Why can owls turn their heads so far? The reason is that their heads are connected to their necks by only one socket, which allows for greater rotation.
Owls are well known for their ability to turn their heads almost all the way around to spot prey or keep an eye on predators. This ability gives them a significant advantage in the wild. Owls can rotate their heads 270˚ in either direction, which means they can look to the left and continue turning until they are looking over their right shoulder. However, they cannot turn their heads in a full 360˚ circle. In comparison, most humans can turn their heads about 160˚, and very flexible people might reach 180˚.
One of the main reasons owls need such a wide range of head movement is that they cannot move their eyes. Unlike humans, who can simply move their eyes to look around, owls have eyes that are shaped like cylinders rather than balls. These cone-shaped eyes are designed to allow for excellent night vision, which is crucial for hunting in the dark. Because their eyes are fixed in place and cannot move, owls must turn their heads to see in different directions.
There are two key differences between human and owl necks. First, humans have two vertebrae connecting the skull to the spine, while owls have only one, which allows for greater rotation. Additionally, owls have more vertebrae in their necks, making their necks more flexible. Another important factor is the structure of their blood vessels. In humans, the arteries that supply blood to the brain pass through the vertebrae in the neck. When we turn our heads too far, these arteries can become constricted, cutting off blood flow to the brain. Owls have evolved to have more blood vessels in their necks, allowing blood to continue flowing even when one vessel is pinched. They also have an enlarged artery near the skull that stores extra blood, ensuring a constant supply to the brain.
These adaptations allow owls to turn their heads much farther than humans can without risking a loss of blood flow to the brain.
Questions:
- Why can owls turn their heads 270˚?
a) They have longer necks
b) Their heads are connected by one socket, allowing greater rotation
c) They have special muscles
d) They have smaller heads - What is one reason owls need to turn their heads so much?
a) They cannot move their eyes
b) They can see in the dark
c) They have large wings
d) They can fly fast - How are owl’s eyes different from human eyes?
a) They are round and can move
b) They are shaped like cylinders and cannot move
c) They are smaller and round
d) They are larger and round - How far can a human typically turn their head?
a) 360˚
b) 270˚
c) 160˚
d) 90˚ - What is the purpose of the enlarged artery near an owl’s skull?
a) To help the owl breathe better
b) To store extra blood for the brain during head rotation
c) To make the owl’s neck stronger
d) To help the owl see better at night - Why can’t humans turn their heads as far as owls?
a) Their necks are too short
b) Their blood vessels could become pinched, cutting off blood flow to the brain
c) Their heads are too heavy
d) They have fewer vertebrae - What happens to an owl’s blood flow when it turns its head?
a) The blood stops flowing
b) The blood finds another route through different vessels
c) The blood moves faster
d) The blood flows to the wings - How does the structure of an owl’s neck differ from that of a human?
a) Owls have more vertebrae and only one vertebra connects the skull to the spine
b) Owls have fewer vertebrae
c) Owls have a longer neck
d) Owls have stronger neck muscles - Why do owls have cone-shaped eyes?
a) To see better at night
b) To look more intimidating
c) To make their heads lighter
d) To help them fly faster - What prevents humans from turning their heads too far?
a) Their muscles are too weak
b) Their bones and blood vessels stop them from cutting off blood flow
c) Their necks are too short
d) Their heads are too heavy
Answers:
- b) Their heads are connected by one socket, allowing greater rotation
- a) They cannot move their eyes
- b) They are shaped like cylinders and cannot move
- c) 160˚
- b) To store extra blood for the brain during head rotation
- b) Their blood vessels could become pinched, cutting off blood flow to the brain
- b) The blood finds another route through different vessels
- a) Owls have more vertebrae and only one vertebra connects the skull to the spine
- a) To see better at night
- b) Their bones and blood vessels stop them from cutting off blood flow
Advanced C1 (英検1級) Version:
Article:
Why can owls turn their heads so far? The answer lies in the unique anatomical features of their necks and the structure of their blood vessels.
Owls are well-known for their remarkable ability to rotate their heads up to 270˚ in either direction, allowing them to keep watch for prey and predators without moving their bodies. This ability is a significant advantage, as it enables owls to stay hidden and quiet while observing their surroundings. However, contrary to popular belief, owls cannot turn their heads a full 360˚. For comparison, most humans can only turn their heads about 160˚, with particularly flexible individuals possibly reaching 180˚.
One of the primary reasons owls need such extensive head rotation is their inability to move their eyes. Unlike humans, whose round eyeballs can move within their sockets, owls have cylindrical eyes that are fixed in place. These cone-shaped eyes, which allow for exceptional night vision, are essential for hunting in low light conditions. However, because their eyes cannot move, owls must rely on turning their heads to see in different directions.
The differences between human and owl necks are key to understanding how owls achieve such a wide range of motion. Humans have two vertebrae, C1 and C2, that connect the skull to the spine, forming the atlantoaxial joint. This joint allows for head rotation, but only up to a certain limit, as the bones, ligaments, and muscles restrict further movement to prevent injury. In contrast, owls have only one vertebra connecting the skull to the spine, which allows for much greater rotation. Additionally, owls have more vertebrae in their necks, providing added flexibility. Another crucial adaptation is the structure of their blood vessels. In humans, the arteries that supply blood to the brain pass through the vertebrae in the neck. When we turn our heads, these arteries can become constricted, potentially cutting off blood flow to the brain. Owls, however, have evolved to have more blood vessels in their necks, allowing blood to continue flowing even when one vessel is pinched. Moreover, their arteries enlarge just below the skull, creating a reservoir of blood that ensures the brain receives a steady supply of oxygen even during extreme head rotations.
These anatomical adaptations enable owls to turn their heads much farther than humans can, without risking a loss of blood flow to the brain. This remarkable flexibility is a testament to the owl’s evolution as a highly specialized nocturnal hunter.
Questions:
- What anatomical feature allows owls to turn their heads so far?
a) Their large wings
b) The unique structure of their necks and blood vessels
c) Their lightweight skulls
d) Their powerful muscles - How far can owls rotate their heads?
a) 180˚
b) 270˚
c) 360˚
d) 90˚ - Why can’t owls move their eyes?
a) Their eyes are too small
b) Their eyes are cylindrical and fixed in place
c) They don’t need to move their eyes
d) Their skulls are too large - What is the primary difference between human and owl necks?
a) Owls have more vertebrae and only one vertebra connects the skull to the spine
b) Owls have fewer vertebrae
c) Owls have longer necks
d) Owls have stronger neck muscles - How do owls maintain blood flow to their brains when turning their heads?
a) Their hearts pump faster
b) Their blood vessels find alternative routes and their arteries near the skull enlarge
c) Their neck muscles help push blood to the brain
d) They have more oxygen in their blood - Why can’t humans turn their heads as far as owls?
a) Their necks are shorter
b) Their blood vessels could become constricted, cutting off blood flow to the brain
c) Their heads are too heavy
d) Their muscles are too weak - What would happen if humans tried to turn their heads as far as owls?
a) They would see behind them
b) They could cut off blood flow to the brain, leading to potential injury
c) They would lose their balance
d) They would increase their field of vision - Why are owl’s eyes shaped like cylinders?
a) To allow for better night vision
b) To reduce their weight
c) To make them look more intimidating
d) To help them fly faster - What is the atlantoaxial joint in humans?
a) The joint connecting the skull to the spine, allowing for head rotation
b) The joint in the knee
c) The joint in the elbow
d) The joint in the wrist - What is the main advantage of an owl’s ability to turn its head so far?
a) It helps them see better in the dark
b) It allows them to stay hidden and observe their surroundings without moving
c) It helps them fly faster
d) It improves their balance
Answers:
- b) The unique structure of their necks and blood vessels
- b) 270˚
- b) Their eyes are cylindrical and fixed in place
- a) Owls have more vertebrae and only one vertebra connects the skull to the spine
- b) Their blood vessels find alternative routes and their arteries near the skull enlarge
- b) Their blood vessels could become constricted, cutting off blood flow to the brain
- b) They could cut off blood flow to the brain, leading to potential injury
- a) To allow for better night vision
- a) The joint connecting the skull to the spine, allowing for head rotation
- b) It allows them to stay hidden and observe their surroundings without moving
Original Version:
Article:
Why can owls turn their heads so far? Because their heads are only connected by one socket, which can rotate.
Owls are renowned for several things. One of them is their ability to swivel their heads completely around so they can keep an eye out for prey or predators. Being able to turn their heads without having to move gives them many advantages and helps keep them safe. They can turn their heads more quietly than they could turn their whole body, staying hidden. However, they cannot rotate their heads completely around. They can rotate them 270˚ in either direction. That means they can look to their left and keep going until they are looking out across their right shoulder. Then they have to swivel back to the front to go the other way. Most humans can rotate their heads about 160˚, and very flexible people can probably go to about 180˚.
Obviously, it is useful to be able to see behind you, but why would an owl need so much neck movement? The main reason is that owls cannot move their eyes. If we want to look behind, we don’t need to turn our heads so they are pointing backwards. When we turn our heads 90˚ so they are level with our shoulder, we can move our eyes and see behind. Owls cannot do this. We can move our eyes because we have eyeballs that can move in the eye socket. Owls don’t have eyeballs; they have eye cylinders. Owls hunt at night, which means they need very good night vision. The cornea is the part of the eye that lets in light, and to be able to see when there is not much light, like at night, requires a very big cornea. Owls have enormous corneas, but they only have very small skulls, and that size cornea on a round, moving eye would not fit in their head. So, they have cone-shaped eyes that can accommodate the cornea, but those cone-shaped eyes cannot move. That means they have to rotate their heads to see.
What is the difference between the necks of a human and an owl? There are two main differences. The first difference is the way the skull connects to the spine. Our skull is connected to the spine with two vertebrae: the C1 and the C2 vertebrae. Together, these two vertebrae are called the atlantoaxial joint. C1 is at the top and it can move forwards and backwards. This is what we use when we nod our heads or look up and down. C1 is shaped like a ring. C2 is underneath and has a peg-shaped projection that the ring of C1 fits over, and this rotates from side to side. The bones, ligaments, and muscles turn and stretch far enough for the head to turn 180˚ at most, and won’t turn any more than that. Owls only have one vertebra that connects to the skull, and this can rotate far more than our two. They also have a lot more smaller vertebrae, which add flexibility. Owls have holes in their vertebrae that hold air sacs, meant to cushion the neck, as well.
However, the flexible neck is not the real reason why they are able to turn their heads so far. The real reason is the way their blood vessels work. The arteries that provide the blood to our brain run up through holes in our vertebrae, up through the neck, and into the skull from the bottom. These arteries pass through the atlantoaxial joint. As we turn our heads, they constrict. If we keep turning our heads, they will be pinched so much that blood flow to the brain will be cut off. This is quite dangerous and is the reason why
our muscles, bones, and ligaments don’t let us twist our heads further. Owls have evolved two ways to overcome this problem. First, they have far more blood vessels going through their neck and spine than we do. When they twist their head and blood gets cut off from one vessel, it can find a route through another vessel. There is always a path for the blood to take. Second, their arteries get larger above the neck, just under the skull. This enlarged artery holds more blood and can supply the brain with blood and oxygen when the owl turns its head and the blood vessel gets pinched off. All of these adaptations allow the owls to turn their heads as far as they can.
Questions:
- Why can owls turn their heads so far?
a) Because their heads are very light
b) Because their necks are connected by one socket, allowing greater rotation
c) Because they have strong neck muscles
d) Because they have large eyes - How far can an owl rotate its head?
a) 360˚
b) 270˚
c) 180˚
d) 90˚ - What is the main reason owls need such extensive neck movement?
a) Their wings are too large
b) They cannot move their eyes
c) They have very small heads
d) They need to see in all directions at once - How are owl’s eyes different from human eyes?
a) They are round and can move
b) They are cylindrical and fixed in place
c) They are larger and can move
d) They are smaller and cannot see well at night - What is the atlantoaxial joint in humans?
a) The joint connecting the skull to the spine, allowing for head rotation
b) The joint in the knee
c) The joint in the elbow
d) The joint in the wrist - How do owls maintain blood flow to their brains when turning their heads?
a) Their hearts pump faster
b) Their blood vessels find alternative routes, and their arteries near the skull enlarge
c) Their neck muscles help push blood to the brain
d) They have more oxygen in their blood - What prevents humans from turning their heads as far as owls?
a) Their necks are shorter
b) Their blood vessels could become constricted, cutting off blood flow to the brain
c) Their heads are too heavy
d) Their muscles are too weak - What happens if humans try to turn their heads too far?
a) They could cut off blood flow to the brain, leading to potential injury
b) They would increase their field of vision
c) They would see behind them
d) They would lose their balance - What is the main advantage of an owl’s ability to turn its head so far?
a) It allows them to stay hidden and observe their surroundings without moving
b) It helps them fly faster
c) It improves their balance
d) It helps them see better in the dark - What would happen if an owl’s blood vessels were not adapted for head rotation?
a) The owl would not be able to rotate its head as far
b) The owl would become dizzy
c) The owl would see less clearly
d) The owl would have stronger neck muscles
Answers:
- b) Because their necks are connected by one socket, allowing greater rotation
- b) 270˚
- b) They cannot move their eyes
- b) They are cylindrical and fixed in place
- a) The joint connecting the skull to the spine, allowing for head rotation
- b) Their blood vessels find alternative routes, and their arteries near the skull enlarge
- b) Their blood vessels could become constricted, cutting off blood flow to the brain
- a) They could cut off blood flow to the brain, leading to potential injury
- a) It allows them to stay hidden and observe their surroundings without moving
- a) The owl would not be able to rotate its head as far
