![]() Rarely, the worms can spread to parts of the body such as the liver, lungs or eyes. The worms usually die or pass out in your poo within a few months without you noticing. Most people who swallow the worm eggs that cause toxocariasis do not become ill. Toxocariasis cannot be spread between people. It's usually caught from soil or sand that has contained worm eggs for a few weeks or months. Toxocariasis is not caught from fresh poo. You can become infected if poo, soil or sand containing these eggs gets in your mouth. Toxocariasis is caused by worms found in some dog, cat and fox poo.Īnimals with these worms in their digestive system can pass out worm eggs in their poo. It's rare, but can sometimes cause serious problems. The Wide World of Pupil Shapesīanks and his colleagues only studied land animals, but round, horizontal, and vertical are just the tip of the iceberg when it comes to pupil shapes: There are w-shaped pupils, crescent-shaped pupils, heart-shaped pupils, and more.Toxocariasis is an infection caused by small worms found in the poo of some dogs, cats and foxes. Bigger cats and wolves, on the other hand, have round pupils because they’re taller and need to chase down a kill rather than pouncing on it. Meanwhile, the team found that vertical, slit-shaped pupils help small ambush predators like cats and snakes judge the distance of prey and other objects so they know how far they have to pounce. In other words, goats have weird eyes because they help keep goats alive. After watching grazing animals at the zoo, though, the researchers found that their eyes rotate to stay horizontally aligned with the ground whether their heads are upright or face down in the grass.įor a land animal that’s in danger of being eaten by something else and has few options besides being aware of its surroundings and running away, the researchers say that a long horizontal pupil seems to be ideal. ![]() Of course, those benefits don’t apply if the pupil stays oriented the same way and becomes vertically aligned when the animal tilts its head to graze. A long horizontal pupil also enhances the image quality of objects ahead of and behind the animal, and helps the eye capture more light along the ground and less dazzling overhead light. Horizontal pupils help here, the team found, because their shape creates a sharp panoramic view that’s wider and shorter than what you’d get with a round or vertical pupil and lets the animal see nearly all around itself. Horses, like goats, have horizontal pupils. ![]() “On the other hand, they must see sufficiently clearly in the forward direction to guide rapid locomotion over potentially rough terrain.” ![]() “On the one hand, these animals must see panoramically to detect predators that could approach from various directions,” the researchers write. Their eyes need to be able to do two things to support that strategy. Goats and other grazing animals (like deer, cattle, and moose) that are hunted by predators have a pretty simple strategy for not being eaten: look out for danger and run away if they see it. Why Horizontal Pupils Help Prey Animals Like Goats To find out what those advantages might be, the researchers analyzed the abilities of the two pupil shapes and how they could serve the different visual requirements of predators and prey. The predator-prey divide in pupil shape suggests that the hunters and the hunted gain some advantage from having a specific type of pupil. Predatory animals that ambush their prey tend to have vertical slit pupils, while herbivores that are prey for other animals usually have horizontal pupils. Cats, ambush hunters, have vertical slits for pupils / Kai Fagerström swe/Moment/Getty Imagesīanks and his team looked at the eyes of 214 different species of land animals, and found a clear relationship between the shape of their pupils and their ecological role.
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