However, humans have lots of colour sensitive cells in our retina that need lots of light in order to work well (mostly clustered at the center of our vision) which gives great colour detail during the day, but which don't actually work at all in low light (which is why you see in black and white and can see things better by not looking directly at them when it is very dark). The round pupil will be able to give the 'best' optical performance but it is more difficult to be able to close the pupil the the same extent as with slitted pupils (although exceptions do exist). This might also be why cats eyes become very wide just before attacking so they have a better perception- however I suspect they will have the equivalent of sunspots after doing so because of the extra light saturating their retina. ![]() However, when it is dark and their pupils open up they take on a circular appearance which will remove these effects. moving animals) better than vertical (i.e. However, the slit will cause optical effects on the vision, such as being able to view horizontal motion (i.e. The vertical slits are generally able to have a greater range of movement and can shut out more light- which is good if your retinas contain lots of low light sensitive receptors for very low light levels at night that will be overloaded in daylight where the light levels are thousands of times brighter. More than meets the eye: change in pupil shape by a mock viper Frontiers in Ecology and the Environment, 14 (8), 453-454 DOI: 10.1002/fee.Yup, as already said the vertical slit pupils are for more nocturnal use and the round pupils for daytime(ish). Silva, I., Crane, M., Artchawakom, T., Suwanwaree, P., & Strine, C. For animals that don't have super strength or speed, a less mild-mannered disguise might be just enough to let them survive another day. Another snake in this region, the Malayan bridle snake, mimics a venomous snake called the Malayan krait not just in its coloration, but by hiding its head under its coils when threatened. "Appearing dangerous might be a last resort, when all else fails," the authors write. If the snakes were just trying to hide, it would make sense to disguise their pupils sooner. But the researchers note that they only saw snakes change their pupils after a human touched them, and not when someone was merely nearby. Or maybe slit eyes are harder for predators to see by shrinking its pupil to a slit, a snake might make its head blend in better with its surroundings. For example, maybe shrinking their pupils improves mock vipers' vision during an attack. The authors think the mock viper may have evolved to mimic this snake. A visually oriented predator would likely have a hard time distinguishing the slit-eyed mock viper from a dangerous true viper. Mock vipers share their range in this part of the world with the similar-looking, but very venomous, Malayan pit viper. The authors think this ruse might help mock vipers defend themselves from hungry animals. But if a threatening animal (say, a human scientist) comes close enough, it squeezes its pupil into a slit. When the snake is relaxed, its pupil is round. They found that the mock viper does, in fact, have a shape-shifting pupil. Had someone made a mistake? Or did the mock viper have a trick up its non-sleeve that no one had noticed before? The researchers explored the question further by methodically spooking some snakes and observing their reactions. Thinking that he had picked up a viper, he instinctively dropped the animal, which immediately fled into the underbrush. However, as one team member grasped the snake behind the head, he noticed that the eyes had shifted to completely vertical slits. In the summer of 2012, researchers from Thailand's Sakaerat Environmental Research Station were doing fieldwork in a forest in northeastern Thailand when they came across a small reptile basking in the sun:Īsed on careful visual inspection we confirmed that the snake was in fact a mock viper because it had round pupils instead of the vertical slit pupils of true vipers. So imitating a more dangerous snake might help mock vipers scare off potential predators. Mock vipers carry only a mild venom they're harmless to humans, for example. Other details are different, though, such as the mock viper's round pupils. Like true vipers, mock vipers have triangular heads. ![]() ![]() Actual vipers are a widespread family of venomous snakes. It's common across much of Asia, and-as you might have guessed from its name-looks a lot like a viper. The mock viper ( Psammodynastes pulverulentus ) is mild-mannered, not superpowered. This makes it resemble a much more dangerous animal. One snake hides its identity using a similar trick: when threatened, it changes the shape of its pupils. Superman donned glasses to disguise himself and blend in with other people.
1 Comment
|
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |