There are 15 species of hedgehogs, most of which are found in the wild in Africa, Asia and Europe. These little, rodent-like critters are covered in spines, which provide them a great deal of protection. Their eyesight is poor, but their keen hearing and sharp sense of smell help them get by quite well in the world.
No Glasses Necessary
Compared to humans, hedgehogs have poor eyesight. That's OK, however, because they don't really use their eyesight all that much. Their limited eyesight allows them to see the outlines of objects, such as a tree, and their color vision is limited to shades of cream and brown. Their binocular vision is limited and they have poor depth perception. As poor as their vision is, it's fine for them because hedgehogs are nocturnal animals, emerging from their nests at night to forage for food.
Small Ears, Big Hearing
Don't feel bad for hedgehogs because their eyesight isn't very good; their other senses make up for this shortcoming. Hedgehogs may not have giant ears, but their ears are positioned for picking up important sounds. Their ears are also sensitive, allowing them to pick up high tones. According to Louisiana State University, hedgehogs have a hearing frequency range between 250 and 45,000 Hz. They can't hear low-pitched sounds as well as humans can, who can hear down to 64 Hz, but it's much higher than the human range of 23,000 Hz.
Use Your Ears
Good hearing is necessary for helping hedgehogs find their food. Their ability to hear high frequencies means they can hear prey as well as potential predators. Unfamiliar or loud noises prompt hedgehogs to take a defensive posture, ducking their heads. As well, good hearing helps hedgehogs orient themselves as they take on tasks such as crossing roads. If they hear something of interest, they'll stand very still to ensure they can hear even better, as their spines rustle and make distracting noise when they walk.
The Nose Knows
As good as hedgehog hearing is, it's only their second most valuable sense. Their sense of smell is their most important and used sense. Their sharp noses sniff out supper as well as intruders, picking up scents in the breeze. These guys are always sniffing as they walk, able to pick up the scent of dinner under as much as an inch of soil. They also can detect other hedgehogs by scent.
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