Animals Wildlife 10 Fun Facts About Hedgehogs By Melissa Breyer Editorial Director Hunter College F.I.T., State University of New York Cornell University Melissa Breyer is Treehugger’s editorial director. She is a sustainability expert and author whose work has been published by the New York Times and National Geographic, among others. our editorial process Melissa Breyer Updated October 21, 2020 Supakrit Tirayasupasin / Getty Images Share Twitter Pinterest Email Animals Wildlife Pets Animal Rights Endangered Species The hedgehog is a spiny nocturnal forager found across the globe. There are 17 species of hedgehogs, and these loners can make a home just about anywhere — deserts, parks, or local gardens. When they are out searching for food, they rely heavily on their sharp quills and ability to stop, drop, and roll into a ball for protection against predators. From their endearing pig-like snout to their natural ability to fight off snake venom, discover the most fascinating facts about hedgehogs. 1. Hedgehogs Were Named for Their Unique Foraging Methods It’s no surprise that hedgehogs are exceptional foragers — it’s how they were named. They root through “hedges” seeking their prey — mostly insects, as well as worms, centipedes, bird eggs, snails, mice, frogs, and snakes — while emitting snorts, squeals, and grunts with their “pig-like” snouts. Their long snouts also provide a strong sense of smell, and their curved claws make them exceptional diggers, both of which are necessary for these nocturnal hunters. 2. A Group Is Called an Array Dieter Hopf / Getty Images Don’t expect to find many large gatherings of hedgehogs. Notorious loners, hedgehogs only meet up for mating. When the male hedgehog, or boar, finds a female hedgehog, or sow, he circles her repeatedly in a mating ritual. After mating, the boar leaves the sow immediately, and she gives birth to four to six hoglets about a month later. The sow doesn’t share her home for long; the young hoglets are weaned and live on their own at about four to six weeks. 3. They Live in a Variety of Habitats The 17 species of hedgehogs live across the globe. They are found in Europe, Asia, and Africa, and are an introduced species in New Zealand. Hedgehogs have adaptations that allow them to live in forests, deserts, savannahs, parks, and home gardens. Depending on where they live, they may nest under small bushes or rocks or dig burrows in the soil. 4. Their Earliest Relatives Lived About 125 Million Years Ago In 2015, a team of scientists working in Spain discovered fossilized remains of a mammal related to the hedgehog. This finding was especially important as it was the first time scientists observed spine-like structures in Mesozoic mammals. The animal’s size, as well the existence of keratin structures, led scientists to compare the 125-million-year-old fossil to both spiny mice and hedgehogs. 5. They Have a Built-in Suit of Armor Hedgehogs can thank their spines for their signature look. They are actually one-inch modified hairs made of keratin that cover the critters’ back and sides. There are between 5,000 to 7,000 spines, or quills, on an average adult hedgehog. They are neither poisonous nor barbed, and unlike the quills of a porcupine, the hedgehog's spines stay firmly attached to the animal. Most hedgehogs have quills from birth. Some are underneath a layer of fluid-filled skin and others are covered by a membrane. The hoglets’ first spines are much softer and are replaced with stronger spines as they grow. 6. They Roll Into a Ball to Protect Themselves petrzurek / Getty Images When hedgehogs feel threatened or alarmed, they curl themselves into spiny little balls to protect themselves and deter predators. In this rolled shape, hedgehogs are much less appealing to badgers, foxes, and other predators. When they curl up, all of their spines point out, which also protects their face, chest, legs, and stomach because those areas are covered in fur, not quills. 7. They Don't All Hibernate Since hedgehogs live in a variety of climates across the globe, some species need to hibernate to get through cold winters. Hedgehogs in desert regions may remain awake all year or experience a bout of torpor lasting 24 hours or less. In the coldest regions, hedgehogs may hibernate for as long as six months; they eat prior to hibernation and store fat to last several weeks. During this time, hedgehogs awaken, forage for food, and return to their slumber. Hedgehogs are able to adjust their schedule and in warmer climates or when winters are especially mild, they may not hibernate at all. 8. They Practice Self-Anointing Hedgehogs take part in a unique type of self-anointing behavior. The mammals will lick and chew toxins and other irritating substances, creating a frothy mixture that they rub onto their skin and spines. Scientists are not quite sure why hedgehogs do this, but hypotheses range from making themselves poisonous to predators to a behavior associated with mating or communication. 9. They Are Naturally Immune to Snake Venom Ipinchuk / Getty Images Like opossums, European hedgehogs have proteins in their blood that neutralize and provide some natural immunity against snake venom. Other animals like mongooses, honey badgers, and pigs have also developed an evolutionary convergent adaptation to snake venom resistance. The value of resistance to snake venom in hedgehogs is significant, as they are able to prey on and even withstand bites from venomous snakes. The immunity is not 100 percent, however, and if stricken by a more virulent snake, the hedgehog may still succumb to the bite. 10. They Can Pass Infections to Humans Known as zoonoses, hedgehogs can transmit viruses or parasites to humans. Cases involve direct contact and most often occur in owners of pet hedgehogs. The Centers for Disease Control and Prevention warns that human contact with hedgehogs can result in salmonella infections as well as Trichophyton erinacei, also known as ringworm, even in healthy looking animals. Hedgehogs also carry and can transmit ectoparasites like ticks, fleas, and mites. View Article Sources Roberts, Colin. "Erinaceus Europaeus (Western European Hedgehog)." Animal Diversity Web. Martin, Thomas et al. "A Cretaceous Eutriconodont and Integument Evolution in Early Mammals." Nature, vol. 526, no. 7573, 2015, pp. 380-384, doi:10.1038/nature14905. "Spines and Quills." Animal Diversity Web. McAllan, B. M., and F. Geiser. "Torpor During Reproduction in Mammals and Birds: Dealing with an Energetic Conundrum." Integrative and Comparative Biology, vol. 54, no. 3, 2014, pp. 516-532, doi:10.1093/icb/icu093 Messer, Emily J. E., and Mark T. Bowler. "Anointing." Encyclopedia of Animal Cognition and Behavior, 2017, pp. 1-3, doi:10.1007/978-3-319-47829-6_863-1 Holding, Matthew L., et al. "Venom Resistance as a Model for Understanding the Molecular Basis of Complex Coevolutionary Adaptations." Integrative and Comparative Biology, vol. 56, no. 5, 2016, pp. 1032-1043, doi:10.1093/icb/icw082 Drabeck, Danielle H., et al. "Why The Honey Badger Don't Care: Convergent Evolution of Venom-Targeted Nicotinic Acetylcholine Receptors in Mammals that Survive Venomous Snake Bites." Toxicon, vol. 99, 2015, pp. 68-72, doi:10.1016/j.toxicon.2015.03.007 "Do Hedgehogs Carry Bovine Tuberculosis and/or Other Diseases that Pose a Danger to Humans or Livestock?" Wildlife Online. "Ringworm in Hedgehogs." Garden Wildlife Health. "Salmonella Infections Linked to Pet Hedgehogs." Centers for Disease Control and Prevention, 2019.