G. Fischer, 1814
A hedgehog is any of the spiny mammals of the subfamily Erinaceinae, which is in the order Erinaceomorpha. There are seventeen species of hedgehog in five genera, found through parts of Europe, Asia, Africa and New Zealand (by introduction). There are no hedgehogs native to Australia, and no living species native to the Americas. Hedgehogs share distant ancestry with shrews (family Soricidae), with gymnures possibly being the intermediate link, and have changed little over the last 15 million years. Like many of the first mammals, they have adapted to a nocturnal way of life. Hedgehogs' spiny protection resembles that of the unrelated rodent porcupines and monotreme echidnas.
The name hedgehog came into use around the year 1450, derived from the Middle English heyghoge, from heyg, hegge ("hedge"), because it frequents hedgerows, and hoge, hogge ("hog"), from its piglike snout. Other names include urchin, hedgepig and furze-pig. The collective noun for a group of hedgehogs is array or prickle.
Hedgehogs are easily recognized by their spines, which are hollow hairs made stiff with keratin. Their spines are not poisonous or barbed and, unlike the quills of a porcupine, cannot easily be removed from the hedgehog. However, spines normally come out when a hedgehog sheds baby spines and replaces them with adult spines. This is called "quilling". When under extreme stress or during sickness, a hedgehog can also lose spines.
A defense that all species of hedgehogs possess is the ability to roll into a tight ball, causing all of the spines to point outwards. However, its effectiveness depends on the number of spines, and since some of the desert hedgehogs evolved to carry less weight, they are much more likely to try to run away and sometimes even attack the intruder, trying to ram into the intruder with its spines; rolling up into a spiny ball is used by those species as a last resort. There are a different number of predators for different species: while forest hedgehogs have relatively few predators, primarily birds (especially owls) and ferrets, smaller species like the long-eared hedgehog are preyed on by foxes, wolves and mongooses.
Hedgehogs are primarily nocturnal, although, depending on the species, they may be more or less active during the day. The hedgehog sleeps for a large portion of the daytime either under cover of bush, grass, rock or in a hole in the ground. Again, different species can have slightly different habits, but in general hedgehogs dig dens for shelter. All wild hedgehogs can hibernate, although not all do; hibernation depends on temperature, species, and abundance of food.
The hedgehog's back is made up of two large muscles, which control the positioning of its quills. There are about 5,000 to 6,500 quills on the average hedgehog, and these are strong on the outer surface, but filled with air pockets on the inside. The hedgehog uses its quills to protect itself from predators, using muscles which draw their quilled skin to cover their full body, and pulling in the parts of their bodies not covered, such as their head, feet, and belly. This form of defense is the hedgehog's most successful, but is usually their last resort.
Hedgehogs are fairly vocal and communicate through a combination of grunts, snuffles and/or squeals, depending on species.
Hedgehogs occasionally perform a ritual called anointing. When the animal encounters a new scent, it will lick and bite the source, then form a scented froth in its mouth and paste it on its spines with its tongue. The specific purpose of this ritual is unknown, but some experts believe anointing camouflages the hedgehog with the new scent of the area and provides a possible poison or source of infection to predators poked by their spines. Anointing is sometimes also called anting because of a similar behavior in birds.
Similar to opossums, mice and moles, hedgehogs have some natural immunity against snake venom due to the protein erinacin in the animal's muscular system, although it is only available in small amounts, and so a viper bite, for example, may kill the hedgehog anyway. In addition, hedgehogs are one of four known mammalian species which possess mutations in the nicotinic acetylcholine receptor that protects against another snake venom, α-neurotoxin. Pigs, honey badgers, mongooses, and hedgehogs all have modifications to the receptor pocket which prevents the snake venom α-neurotoxin from binding. These represent four separate, independent mutations.
Although traditionally classified in the now abandoned order Insectivora, hedgehogs are not exclusively insectivores but are omnivorous. They feed on insects, snails, frogs and toads, snakes, bird eggs, carrion, mushrooms, grass roots, berries, melons and watermelons. Berries constitute a major part of an Afghan hedgehog's diet in early spring after hibernation.
Reproduction and lifespan
Depending on the species, the gestation period is 35–58 days. The average litter is 3–4 newborns for larger species and 5–6 for smaller ones. As with many animals, it is not unusual for an adult male hedgehog to kill newborn males.
Hedgehogs have a relatively long lifespan for their size. Larger species of hedgehogs live 4–7 years in the wild (some have been recorded up to 16 years), and smaller species live 2–4 years (4–7 in captivity), compared to a mouse at 2 years and a large rat at 3–5 years. Lack of predators and controlled diet contribute to a longer lifespan in captivity (8–10 years depending on size).
Hedgehogs are born blind with a protective membrane covering their quills, which dries and shrinks over the next several hours. The infants are born with quills beneath the skin, like pimples, and pass the skin after they have been cleaned.
In Britain, the main predator is the badger. Hedgehogs in the UK have demonstrably lower populations in areas where badgers are numerous, so that British hedgehog rescue societies will not release hedgehogs into known badger territories.
The most common pet species of hedgehog are hybrids of the white-bellied hedgehog or four-toed hedgehog (Atelerix albiventris) and the North African hedgehog (A. algirus). It is smaller than the European hedgehog, and thus is sometimes called the African pygmy hedgehog. Other species kept as pets are the long-eared hedgehog (Hemiechinus auritus) and the Indian long-eared hedgehog (H. collaris).
It is illegal to own a hedgehog as a pet in some US states and some Canadian municipalities, and breeding licenses are required. No such restrictions exist in most European countries with the exception of Scandinavia. In the UK wild hedgehogs are considered endangered and it is illegal to keep one as a pet. In Italy it is illegal to keep wild hedgehogs as pets.
Diet: Domesticated hedgehogs can eat a variety of foods. The basic, and most common, type of food is high protein cat food. In addition, wet cat/dog food may be used to feed domesticated hedgehogs, but dry food is a crucial part of their diet. On occasion treats may be fed to hedgehogs. It’s best to feed treats to hedgehogs only occasionally to keep them healthy. Treats can include, but not limited to, dried/alive mealworms or crickets, and certain types of fruits and vegetables. New foods should be tried in moderation in order to ensure the pets health. In addition, there should always be fresh water in the cage. This can either come from a dropper or water in a bowl.
Habitat: Hedgehogs need plenty of space to explore. Cages for hedgehogs can be varied and offer many options, which can include rabbit/other animal cages, or homemade cages. Cages should be big enough for hedgehogs to run around in and have enough space for the equipment needed for the animal. The floor of the cage should be smooth, not wire, to make sure that the feet of the hedgehog do not get hurt. The top of the cage should be open to create enough air flow. In addition, the cage requires a hideaway for the hedgehog, a wheel, food/water bowl, a heat lamp, an optional thermometer, and toys. On the bottom of the cage there needs to be bedding in order to keep the hedgehog warm and offer them a soft material on their feet. Many materials can be used as bedding including, wood chips, newspaper, and fleece. Only soft material should be used because wire/mesh/rough materials could harm the hog. Sawdust based litter should be avoided because the dust in it can cause lung problems in the animal. Hideaways, which include beds for sleeping, should be always available to hedgehogs. These allow the hedgehogs to relax and sleep in an isolated area to feel safe. Options for hideaways and beds include pet igloos, sleeping pouches, tunnel, half log, and anything that offers them a place to feel safe and comfortable by themselves. Wheels are also a necessity for the cage because it offers the hedgehog daily exercise. The wheel should also be solid and not wire because wire wheels hurt the paws of hedgehogs. Heat lamps are also a necessity for hedgehogs. Hedgehogs need to be in an environment of 75-80 degrees constantly. Heat lamps should be positioned on top of the cage so that it could heat up the entire area. Thermometers are a good option to add to the hedgehog cage because it shows the temperature of the cage at all times, allowing for maximum care for the animal. In addition, toys are great options for hedgehogs because it offers fun time and relaxation.
Grooming: Although hedgehogs are fairly clean animals and rarely need grooming, hedgehog owners are generally advised to maintain their hedgehog's cleanliness through periodic baths. Most owners find it easiest to bathe hedgehogs in a kitchen sink filled with a few inches of water. The ideal frequency of baths depends on a hedgehog's breed and individual tendencies, so owners should consult a trusted breeder or hedgehog expert before developing a bathing schedule. In addition, a hedgehog's nails need to be trimmed. Trimming hedgehog nails can be done carefully with baby nail clippers at home, or by some veterinarian offices trained in hedgehog care.
In areas where hedgehogs have been introduced, such as New Zealand and the islands of Scotland, the hedgehog has become a pest. In New Zealand it causes immense damage to native species including insects, snails, lizards and ground-nesting birds, particularly shore birds. As with many introduced animals, it lacks natural predators.
Eradication can be troublesome. Attempts to eliminate hedgehogs from bird colonies on the Scottish islands of North Uist and Benbecula in the Outer Hebrides were met with international outrage. Eradication began in 2003 with 690 hedgehogs being killed. Animal welfare groups attempted rescues to save the hedgehogs. By 2007, legal injunctions against the killing of hedgehogs were put in place. In 2008, the elimination process was changed from killing the hedgehogs to trapping them and releasing them on the mainland.
Cancer is very common in hedgehogs. The most common is squamous cell carcinoma. Squamous cell spreads quickly from the bone to the organs in hedgehogs, unlike in humans. Surgery to remove the tumors is rare because it would result in removing too much bone structure.
Fatty liver disease is believed by many to be caused by bad diet. Hedgehogs will eagerly eat foods that are high in fat and sugar. Having a metabolism adapted for low-fat, protein-rich insects, this leads to common problems of obesity. Fatty liver disease is one sign, heart disease is another.
Hedgehogs uncommonly transmit a characteristic fungal skin infection to human handlers as well as other hedgehogs. This ringworm or dermatophytosis infection is caused by Trichophyton erinacei, which forms a distinct mating group within the Arthroderma benhamiae species complex.
As with most small mammals living around humans, cars pose a great threat to hedgehogs. Many are run over as they attempt to cross roadways.
In 2006, McDonald's changed the design of their McFlurry containers to be more hedgehog-friendly. Previously, hedgehogs would get their heads stuck in the container as they tried to lick the remaining food from inside the cup. Then, being unable to get out, they would starve to death. Domesticated hedgehogs display this behavior by getting their head stuck in tubes (commonly, lavatory paper tubes) and walking around with the tube on their head. Hedgehog owners often refer to this as "tubing" and promote the behavior by supplying clean tubes. Most owners are considerate enough, however, to cut the tubes lengthwise so as to prevent the hedgehog from remaining trapped against their will. Curiously though, some will still knowingly get themselves stuck for a few hours.
Culinary and medicinal use
Hedgehogs are a food source in many cultures. Hedgehogs were eaten in Ancient Egypt and some recipes of the Late Middle Ages call for hedgehog meat. In the Middle East and especially among Bedouins, hedgehog meat is considered medicinal, and thought to cure rheumatism and arthritis. Romani people still eat hedgehogs, boiled or roasted, and also use the blood and the fat for its supposed medicinal value. During the 1980s, "hedgehog-flavour" crisps were introduced in Britain, although the product did not contain any hedgehog.
Genera and species
Subfamily Erinaceinae (Hedgehogs)
- Genus Atelerix
- Genus Erinaceus
- Genus Hemiechinus
- Genus Mesechinus
- Genus Paraechinus
- European hedgehog
- Echidnas or "spiny anteaters", members of the order Monotremata that have spines
- Hedgehog's dilemma
- Hedgehogs in culture
- Porcupines, two different rodent families which have spines or quills
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|Look up hedgehog in Wiktionary, the free dictionary.|
|Wikimedia Commons has media related to Erinaceidae.|
- Hedgehogs (Species) at DMOZ
- Hedgehog reference at the University of Michigan Museum of Zoology
- Hedgehog facts
- Hedgehog care and advice
- Natural History of European Hedgehogs (Wildlife Online)
- "Hedgehog". Encyclopedia Americana. 1920.