Snowy Owls weigh about 4 pounds. Owl necks are longer and skinnier than they look. The long, thick feathers that cover the neck make it look short and fat. Owls don't have eyeballs. The eyes are long and shaped more like a tube. Owl eyes can't turn in their sockets because of this shape. Owls and the related nightjars including Whip-poor-wills and nighthawks are among the only birds that have a larger upper eyelid than lower eyelid.
That, their forward-facing eyes, and feather-covering at the base of their beak, make them appear more human-like than other birds. Their human-sounding voices are one reason so many cultures throughout the world have stories and folklore about owls. Owls can see in the daytime. Their pupils don't get as small as ours in bright light, so to block out the extra light, they often close their eyes half-way or more.
They may look sleepy or even half asleep when really they are wide awake and alert. Vision cells called rods and cones are in the retina of all animals. But birds and primates including humans have a special area in the retina called the fovea where these vision cells are especially concentrated. In hawks and owls, the fovea is on the upper part of the retina, so things below the owl appear exceptionally clear.
This helps them hunt on the ground. A whip snake trying to get its mouth around a Texas horned lizard may well give up, because it just can't fit the whole thing in. View image of A regal horned lizard P. Instead of puffing up, regal horned lizards roll over. When threatened by a whip snake, the lizard flips onto its back. This exposes a pure white belly, white legs, and the white outline of its spines along its edge — which rather resemble teeth. The lizard also splays its short legs out stiffly at its sides, like a wrestler struggling not to be turned over.
Social Intelligence Test
Some scientists suggest they are playing dead, but Sherbrooke disagrees. He thinks they are advertising their size and spininess. Finally, there is horned lizards' best-known defence: blood squirting. They reserve this for two groups of predators: cats and canids , the group that includes dogs, coyotes and wolves. The process is quite simple. A pouch below the lizard's eyes, the ocular sinus, swells as it fills with blood. With a sudden surge of pressure, blood forcefully squirts out in a stream that can travel up to 6ft 2m. They shake their heads, they salivate profusely, and try to clear the material out of their mouths.
To show that horned lizards can discern dogs from other large predators, Sherbrooke recruited a golden retriever called Dusty. She was trained to bark, paw and gently nibble at a horned lizard. Within a minute of Dusty barking, each lizard squirted her. In contrast, the lizards were less concerned when Sherbrooke tried to mimic Dusty's behaviour.
The lizards were not fooled, and mostly ignored his dog impersonation. Canids are not averse to blood, but they dislike horned lizard blood, even though it is not poisonous. The blood contains a chemical that binds to receptors in the canid's mouth: receptors that humans apparently lack.
He never detected anything more than a mild acrid aftertaste. The blood is most effective when delivered directly into the mouth , rather than the eyes or nose.
This might explain why horned lizards often wait until the last second, when they are already in their attacker's jaws, before squirting. The lizards probably get the unpleasant chemical in their blood from their food. They mostly eat ants, and many eat highly venomous harvester ants. A horned lizard will lap up its food with the tip of its sticky tongue.
It's All in the Eyes
It does not chew the ants. Instead, before swallowing, it wraps the ants in strands of thick mucus secreted by special cells at the back of its throat. This protects the lizard from the ants' stings, allowing them to exploit a resource that most animals can't.
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View image of The desert horned lizard P. To make up for it, a horned lizard has to eat a lot of ants, and to do that it needs a big stomach. To accommodate such a large stomach, ant-eaters need to be stocky. Of course, sometimes camouflage, armour and squirting blood aren't enough, and a horned lizard gets eaten anyway. Injuries can include corneal abrasion which is a scratch or a corneal laceration which is a cut.
A corneal injury can cause vision problems and is considered serious. Corneal abrasions can be caused by a foreign particle under your eyelid, poking your eye, or even vigorously rubbing your eyes. A corneal laceration is deeper and usually caused by being hit in the eye with significant force or something sharp. Minor corneal injuries tend to heal on their own within a few days.
In the meantime, you can apply a cold compress to your closed eyelid several times a day for relief. If the injury is more severe, seek immediate treatment.
Some corneal injuries can have a permanent effect on your vision without proper treatment. You may also need antibiotic or steroid eye drops to reduce inflammation and your risk of scarring. A corneal ulcer is an open sore on your cornea that can be caused by different types of infections, including bacterial, viral, or fungal infections. When you blink, the ulcer can feel like an object stuck in your eye.
Your risk of developing a corneal ulcer increases if you wear contact lenses, have severe dry eyes or a corneal injury, or have a viral infection, such as chicken pox, shingles, or herpes. Corneal ulcers require immediate treatment because they can cause permanent damage to your eye, including blindness. Drops to dilate your pupil may also be used to reduce the risk of complications.
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Also known as ocular herpes, eye herpes is an infection of the eye caused by the herpes simplex virus HSV. There are different types of eye herpes, depending on how deep into the layers of the cornea the infection extends. Any potential case of eye herpes warrants a visit to your healthcare provider. You may need antiviral medication or steroid eye drops.
enter Fungal keratitis is a rare fungal infection of the cornea. According to the Centers for Disease Control and Prevention , an injury to the eye, especially with a plant or stick, is the most common way people develop fungal keratitis. As you recover, applying a cold compress can help with the discomfort. You may also want to invest in a good pair of sunglasses to manage the increased sensitivity to light.
Pterygium is a harmless growth of the conjunctiva over the cornea. These growths are usually wedge-shaped and located on the inner corner or middle portion of your eye. The cause of the condition is unknown, but it appears to be linked to exposure to sunlight, dust, and wind.