How do penguins see clearly underwater

Penguins after spending their day catching fish, having fun, preening and taking care of their young spend their nighttime sleeping. Penguins are not nocturnal animals, they are diurnal in nature i. Penguins however do not sleep long nights like humans. They take a lot of short naps throughout the whole day including at night. This is due to the fear of predators such as the Galapagos shark. They sleep in short bursts like most birds and also have their safety in numbers.

During the long winters in the Antarctic for example, male penguins spend most of their time sleeping. Penguins see the world differently from the way humans do. Penguins have been discovered to be able to see the colors humans do and also in ultraviolet vision. Penguins can see in color and are sensitive to violet, blue, and green wavelengths of light, as well as possibly ultraviolet light. Penguins are one of the best divers of the marine world and they can go as far as 1, feet underwater while hunting for food.

Penguins spend most of their life on and in water and only come ashore to breed and raise their chicks before they go in the water again. Penguins are amazing scuba divas and an emperor penguin can go as far 1, feet in water without scuba diving gear.

Scientists have wondered how these birds are able to see perfectly under the water at those depths. But what happened to their eyes? Figure 2 shows a typical penguin eye, with its nearly flat cornea and a somewhat spherical lens.

This is very unusual: The penguin is one of the rare vertebrates with a flattened cornea. Is this feature good or bad? Nature is littered with examples of evolutionary meanderings that have led to remarkable blunders requiring sloppy follow-up. Since the latter is unlikely, some other mechanism must come into play. One hypothesis, based on evidence that penguins severely constrict their pupils in air to about 1mm across , is that the muscular activity that shrinks the pupil also flattens the small portion of the cornea directly in front of the pupil, and thus removes the near-sightedness.

Figure 3 — Refractive errors: Human versus penguin. Cormorants are both abundant and widespread geographically in temperate to sub-polar regions. They are both active fliers and pursuit divers, nesting in cliffs and diving for fish. Their adaptations for hunting in the sea include webbed feet, denser bones than normal birds less hollow , feathers that are water-resistant near the skin for trapping air insulation and water-absorbent elsewhere to reduce buoyancy.

They are usually benthic hunters, descending on average to about 30 feet, but the blue-eye shag has been known to reach feet. Although cormorants spend less time in the water than penguins, they are better foragers. In fact, the great cormorant Phalacrocorax carbo sinensis is the most efficient marine predator on the planet, averaging 17—41 grams of fish per minute spent underwater. Does it? The cornea of the great cormorant is very curved, having a power of about 60 diopters, which is about 20 diopters more than that of the human eye.

Like us, it loses most of that power when immersed in water. These adaptations allow focus in air and in water!!! Like other birds, penguins have a nictitating membrane, sometimes called a third eyelid. This is a clear covering that protects the eye from injury. By wearing a flat diving mask, humans can see clearly underwater.

Light rays entering from water into the flat parallel window change their direction minimally within the window material itself. Penguins have a flattened cornea that refracts light less strongly than human or fish corneas. Their strong eye muscles change the shape of their eye lens to create a sharp, clear image both on land and in water. Penguins rely heavily on visual cues for foraging, making underwater vision a must for survival.

Julie Neiworth, a researcher at Carleton College in Minnesota, once saw a laboratory pigeon land on her computer keyboard's space bar. The pigeon's weight sent the cursor marker skittering across the computer screen. Fascinated by the moving light, the pigeon tracked it across the screen, pecking at it, which prompted Neiworth to test a pigeon's ability to calculate the trajectory of a moving object. Then she taught pigeons that every time they pecked at the moving light and hit it, as scored by electronic sensors in the screen, they would receive their favorite food as a reward.

It is a game, she notes, at which the pigeons excel. And it indicates pigeons have perceptual skills that people do not. Pigeons even do well in a vision scientist's version of art history. Donald Kendrick, a psychologist at Middle Tennessee State University, has been showing pigeons pen-and-ink drawings of birds and mammals from nineteenth-century scientific journals.

If the pigeons can tell bird drawings from mammal drawings by pecking the appropriate slide, they earn a treat. He checks the pigeons by showing them previously unseen drawings, to make sure they are not simply memorizing the pictures.

Recently, Kendrick showed pigeons photographs of landscapes. So the researcher made photographic slides of the yard from various angles, including some angles the pigeons had never seen. The birds distinguished slides of the lab's yard from slides of similar-looking fields. But can pigeons match a photograph with the real object it represents? To find out, Kendrick photographed toy soldiers, little space ships, yo-yos, tiny trucks—"They all came from my son's toy box," he says.

Then he taught the pigeons to peck a slide of a particular toy, such as a yo-yo, to earn a treat. Finally, he put the trained pigeon in a T-shaped maze. On one side of the T was an actual yo-yo. On the other side was a different toy. Psychologist Robert Cook, now at Tufts University, also worked on the photograph tests. He created fantasy creatures by cutting apart drawings and pasting mammal heads on bird bodies, and vice-versa.

He found that pigeons see a picture with a mule's head on a duck's body as a bird. To a pigeon, however, a duck-headed mule is a mammal.

A pigeon brain is small. His pigeons, like Retina the poodle, are apparently happy to help. Donate Today. Sign a Petition.

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