Hedgehog

This article is about the spiny mammal. For other uses, see Hedgehog (disambiguation).

A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introduction. There are no hedgehogs native to Australia and no living species native to the Americas. However, the extinct genus Amphechinus was once present in North America.

Hedgehogs^[1] Temporal range: Late Eocene – Recent PreꞒ Ꞓ O S D C P T J K Pg N
European hedgehog
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Eulipotyphla
Family:	Erinaceidae
Subfamily:	Erinaceinae G. Fischer, 1814
Type genus
Erinaceus Linnaeus, 1758
Genera
Atelerix Erinaceus Hemiechinus Mesechinus Paraechinus

Hedgehogs share distant ancestry with shrews (family Soricidae), with gymnures possibly being the intermediate link, and they have changed little over the last fifteen million years.^[2] Like many of the first mammals, they have adapted to a nocturnal way of life.^[3] Their spiny protection resembles that of porcupines, which are rodents, and echidnas, a type of monotreme.

Etymology

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.^[4] Other names include urchin, hedgepig and furze-pig.

Description

Hedgehogs are easily recognized by their spines, which are hollow hairs made stiff with keratin.^[5] Their spines are not poisonous or barbed and, unlike the quills of a porcupine, do not easily detach from their bodies. However, the immature animal's spines normally fall out as they are replaced with adult spines. This is called "quilling". Spines can also shed when the animal is diseased or under extreme stress. Hedgehogs are usually brown, with pale tips to the spines, though blonde hedgehogs are found on the Channel Island of Alderney.

 

A skin-skeletal preparation

 

Close-up of the last 5 millimetres (0.20 in) of a hedgehog spine (SEM microscopy)

 

A hedgehog that feels threatened can roll into a tight ball.

All species of hedgehogs can roll into a tight ball in self-defense, causing all of the spines to point outwards.^[5] The hedgehog's back contains two large muscles that control the position of the quills. When the creature is rolled into a ball, the quills on the back protect the tucked face, feet, and belly, which are not quilled. Since the effectiveness of this strategy depends on the number of spines, some desert hedgehogs that evolved to carry less weight are more likely to flee or attack, ramming an intruder with the spines; rolling into a spiny ball for those species is a last resort.

Hedgehogs are primarily nocturnal, though some species can also be active during the day. Hedgehogs sleep for a large portion of the day under bushes, grasses, rocks, or most commonly in dens dug in the ground, with varying habits among the species. All wild hedgehogs can hibernate, though not all do, depending on temperature, species, and abundance of food.

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.^[6] 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 purpose of this habit 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.

Like opossums, mice, and moles, hedgehogs have some natural immunity against some snake venom through the protein erinacin in the animal's muscular system, although it is available only in small amounts and a viper bite may still be fatal.^[7] In addition, hedgehogs are one of four known mammalian groups with mutations that protect against another snake venom, α-neurotoxin. Pigs, honey badgers, mongooses, and hedgehogs all have mutations in the nicotinic acetylcholine receptor that prevent the snake venom α-neurotoxin from binding, though those mutations developed separately and independently.^[8]

Olfactory sense

The olfactory regions have not been thoroughly studied in the hedgehog. In mammals, the olfactory part of the brain is covered by neopallium, making it difficult to expose. This difficulty is not insurmountable, as it varies from one species to another.^{[clarification needed]} Tests have suggested that hedgehogs share the same electrical activity as cats.^[9]

Diet

Although traditionally classified in the now abandoned order Insectivora, hedgehogs are omnivorous. They feed on insects, snails, frogs and toads, snakes, bird eggs, carrion, mushrooms, grass roots, berries, melons and watermelons.^[5] Berries constitute a major part of an Afghan hedgehog's diet in early spring after hibernation.^{[citation needed]}

Hibernation

During hibernation, the body temperature of a hedgehog can decrease to about 2 °C (36 °F). When the animal awakes from hibernation, the body temperature rises from 2–5 °C (36–41 °F) back to its normal 30–35 °C (86–95 °F) body temperature.^[10]

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.^[11] The quills emerge through the membrane after the hoglet has been cleaned, or after the membrane falls off.^[12]

Predators

The various species are prey to different predators: while forest hedgehogs are prey primarily to birds (especially owls) and ferrets, smaller species like the long-eared hedgehog are prey to foxes, wolves, and mongooses.

Hedgehog bones have been found in the pellets of the European eagle owl.^[13]

In Britain, the main predator is the European badger. European hedgehog populations in the United Kingdom are lower in areas where badgers are numerous,^[14] and British hedgehog rescue societies will not release hedgehogs into known badger territories.^[15] Badgers also compete with hedgehogs for food.^[16]

Domestication

Main article: Domesticated hedgehog

 

African pygmy hedgehog being held

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).^[17] 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 including Hawaii, Georgia, Pennsylvania, and California,^[18] and some Canadian municipalities, and breeding licenses are required. No such restrictions exist in most European countries with the exception of Scandinavia. In Italy, it is illegal to keep wild hedgehogs as pets.^[19]

Invasive species

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.^[20] 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.^[21]

In 2022, it was reported that the hedgehog population in rural Britain is experiencing a rapid decline, going down by 30%-75% since 2000.^[22]

Diseases

Hedgehogs suffer many diseases common to humans.^[23] These include cancer, fatty liver disease, and cardiovascular disease.

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 are also known to be highly susceptible to pneumonia. Similarly to how pneumonia affects humans, the symptoms for pneumonia in hedgehogs include difficulty breathing and presence of nasal discharge.^[24] This is known to be caused by the Bordetella bronchiseptica bacterium.^[25]

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.^[26]

 

Hedgehog suffering from balloon syndrome before deflating

Hedgehogs can suffer from balloon syndrome, a rare condition in which gas is trapped under the skin as a result of injury or infection and which causes the animal to inflate.

Human influence

 

Hedgehog amulet from Egypt, New Kingdom, Dynasty 18, reign of Amenhotep III - Cleveland Museum of Art

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 Ireland, hedgehogs are one of the most common mammalian road fatalities. Between April 2008 and November 2010 on two stretches of road measuring 227 km and 32.5 km there were 133 recorded hedgehog fatalities. Of another 135 hedgehog carcasses collected from throughout Ireland, there were significantly more males than females collected, with peaks in male deaths occurring in May and June. Female deaths outnumbered males only in August, with further peaks in female deaths observed in June and July. It is suggested that these peaks are related to the breeding season (adults) and dispersal/exploration following independence.^[27]

Domesticated hedgehogs can get their heads stuck in tubes (commonly, toilet paper tubes) and walk around with them on their heads. Owners often refer to this as "tubing" and promote the behavior by supplying lean tubes. Most owners are considerate enough, however, to cut the tubes lengthwise to prevent the hedgehog from remaining trapped against its will. Curiously, some hedgehogs still knowingly get themselves stuck for hours.^[28]

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.^[29] Hedgehogs are traded throughout Eurasia and Africa for traditional medicine and witchcraft. In the Middle East and especially among Bedouins, hedgehog meat is considered medicinal, and thought to cure rheumatism and arthritis.^[30] They are also said to cure a variety of illnesses and disorders from tuberculosis to impotence. In Morocco, inhaling the smoke of the burnt skin or bristles is a purported remedy for fever, male impotence, and urinary illnesses; the blood is sold as a cure for ringworm, cracked skin and warts and the flesh is eaten as a remedy for witchcraft.^[31] Romani people still eat hedgehogs, boiled or roasted, and also use the blood and the fat for its supposed medicinal value.^[32]

In 1981, British publican Philip Lewis developed a line of Hedgehog Flavoured Crisps, whose taste was apparently based on the flavourings used by Romani to bake hedgehogs.^[33][34] As the crisps did not contain any actual hedgehog product, he was forced by the Office of Fair Trading to change the name to Hedgehog Flavour Crisps.^[35]

Genera and species

 

Long-eared hedgehog

Subfamily Erinaceinae (hedgehogs)^[1]

• Genus Atelerix
  • Four-toed hedgehog, Atelerix albiventris
  • North African hedgehog, Atelerix algirus
  • Southern African hedgehog, Atelerix frontalis
  • Somali hedgehog, Atelerix sclateri
• Genus Erinaceus
  • Amur hedgehog, Erinaceus amurensis
  • Southern white-breasted hedgehog, Erinaceus concolor
  • European hedgehog, Erinaceus europaeus
  • Northern white-breasted hedgehog, Erinaceus roumanicus
• Genus Hemiechinus
  • Long-eared hedgehog, Hemiechinus auritus
  • Indian long-eared hedgehog, Hemiechinus collaris
• Genus Mesechinus
  • Daurian hedgehog, Mesechinus dauuricus
  • Hugh's hedgehog, Mesechinus hughi
  • Small-toothed forest hedgehog, Mesechinus miodon
  • Gaoligong forest hedgehog, Mesechinus wangi
• Genus Paraechinus
  • Desert hedgehog, Paraechinus aethiopicus
  • Brandt's hedgehog, Paraechinus hypomelas
  • Indian hedgehog, Paraechinus micropus
  • Bare-bellied hedgehog, Paraechinus nudiventris

See also

• Echidnas or "spiny anteaters", members of the order Monotremata that have spines
• Lesser hedgehog tenrec
• Greater hedgehog tenrec
• Hedgehog's dilemma
• Hedgehogs in culture
• Porcupines, two different rodent families which have spines or quills
• The Hedgehog and the Fox
• Hedgehog flavour crisps

References

1. Hutterer, R. (2005). "Order Erinaceomorpha". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 212–217. ISBN 978-0-8018-8221-0. OCLC 62265494.
2. Reiter C, Gould GC (1998). "Thirteen Ways of Looking at a Hedgehog". Natural History. 107 (6): 52.
3. . WildlifeTrust.org.uk. Archived from the original on 12 February 2013. Retrieved 28 February 2013.
4. Oxford English Dictionary, Online edition. Retrieved 13 July 2007.
5. Attenborough, David (2014). Attenborough's Natural Curiosities 2. Vol. Armoured Animals. UKTV.
6. Drew, Lisa W. (1 June 2005). "Meet the Hedgehog: What feeds on lizards, chews venomous toad skins and coats its spiky body with frothy saliva?". National Wildlife. Reston, Virginia: National Wildlife Federation. Retrieved 12 July 2017.
7. Omori-Satoha, Tamotsu; Yoshio Yamakawab; Dietrich Mebs (November 2000). "The antihemorrhagic factor, erinacin, from the European hedgehog (Erinaceus europaeus), a metalloprotease inhibitor of large molecular size possessing ficolin/opsonin P35 lectin domains". Toxicon. 38 (11): 1561–80. doi:10.1016/S0041-0101(00)00090-8. PMID 10775756.
8. Drabeck, D.H.; Dean, A.M.; Jansa, S.A. (1 June 2015). "Why the honey badger don't care: Convergent evolution of venom-targeted nicotinic acetylcholine receptors in mammals that survive venomous snake bites". Toxicon. 99: 68–72. doi:10.1016/j.toxicon.2015.03.007. PMID 25796346.
9. Adrian, E. D. (1942). "Olfactory reactions in the brain of the hedgehog". The Journal of Physiology. 100 (4): 459–473. doi:10.1113/jphysiol.1942.sp003955. PMC 1393326. PMID 16991539.
10. Suomalainen, Paavo; Sarajas, Samuli (1 August 1951). "Heart-beat of the Hibernating Hedgehog". Nature. 168 (4266): 211. Bibcode:1951Natur.168..211S. doi:10.1038/168211b0. ISSN 0028-0836. PMID 14875055. S2CID 4158610.
11. Litter – Burlington and MIDI (2004-04-19) 10 July 2009 at the Wayback Machine. hamorhollow.com
12. . Hedghogz.co.uk. Archived from the original on 6 September 2013. Retrieved 8 March 2009.
13. . wildlifeinformation.org
14. Hof, A. R.; Bright, P. W. (2010). "The value of agri-environment schemes for macro-invertebrate feeders: Hedgehogs on arable farms in Britain" (PDF). Animal Conservation. 13 (5): 467–473. doi:10.1111/j.1469-1795.2010.00359.x. S2CID 82793575. (PDF) from the original on 6 October 2014. Badger predation of hedgehogs was high in the study site and the main cause of death
15. Where have all the hedgehogs gone ?. Snufflelodge.org.uk. Retrieved 2013-09-05.
16. David Wembridge. "The State of Britain's Hedgehogs 2011" (PDF). The British Hedgehog Preservation Society. (PDF) from the original on 18 May 2013.
17. "The Complete Guide to Hedgehogs". www.petmd.com. Retrieved 16 February 2020.
18. Moss, Laura (1 April 2019). "Hedgehogs are a prickly issue in some states". treehugger.com. from the original on 18 October 2020. Retrieved 18 October 2020.
19. . Corpo Forestale dello Stato. Archived from the original on 2 November 2016. Retrieved 31 August 2014.
20. . Landcare Research media release. 17 September 2003. Archived from the original on 1 October 2003. Retrieved 6 December 2011.
21. Ross, David (14 January 2009). "18 Trappers Sought for Hebrides to Protect Birds from Hedgehogs". The Herald. Retrieved 12 June 2009.
22. "Hedgehog population plummets in UK countryside, research suggests". BBC News. 22 February 2022.
23. . Wildlifeinformation.org. Archived from the original on 26 July 2010. Retrieved 8 March 2009.
24. "Hedgehogs - Diseases". vca_corporate. Retrieved 2 November 2020.
25. "Common Diseases Of Hedgehogs". Bowmanville Veterinary Clinic. Retrieved 2 November 2020.
26. Takahashi, Yoko; Ayako Sano; Kayoko Takizawa; Kazutaka Fukushima; Makoto Miyaji; Kazuko Nishimura (2003). "The epidemiology and mating behavior of Arthroderma benhamiae var. erinacei in household four-toed hedgehogs (Atelerix albiventris) in Japan" (PDF). Japanese Journal of Medical Mycology. 44 (1): 31–8. doi:10.3314/jjmm.44.31. PMID 12590257. (PDF) from the original on 1 November 2003.
27. Haigh, Amy; O'Riordan, Ruth M.; Butler, Fidelma (2014). "Hedgehog Erinaceus europaeus mortality on Irish roads". Wildlife Biology. 20 (3): 155–160. doi:10.2981/wlb.12126.
28. . Hedgehog World. Archived from the original on 15 January 2008. Retrieved 8 March 2009.
29. Pidd, Helen (14 September 2007). "Roast hedgehog and nettle pud – a slap-up feast for ancient Britons". The Guardian. London. Retrieved 12 June 2009.
30. Qumsiyeh, Mazin B. (1996). Mammals of the Holy Land. Texas Tech UP. p. 64. ISBN 978-0-89672-364-1.
31. Nijman, V.; Bergin, D. (2015). "Trade in hedgehogs (Mammalia: Erinaceidae) in Morocco, with an overview of their trade for medicinal purposes throughout Africa and Eurasia". Journal of Threatened Taxa. 7 (5): 7131–7137. doi:10.11609/JoTT.o4271.7131-7.
32. Wood, Manfri Frederick (1979). In the Life of a Romany Gypsy. J.A. Brune. pp. 80–81. ISBN 978-0-7100-0197-9.
33. Emerson, Richard (24 April 2012). Read the Label!: Discover what's really in your food. Random House. p. 81. ISBN 978-1-4481-4684-0.
34. "Hedgehog Crisps' Welshpool inventor dies, aged 74". Shropshire Star. 28 February 2017. Retrieved 7 August 2021.
35. "Hedgehog Crisps' Welshpool inventor dies, aged 74". Shropshire Star. 28 February 2017. Retrieved 15 September 2021.{{cite web}}: CS1 maint: url-status (link)

External links

 

Look up hedgehog in Wiktionary, the free dictionary.

 

Wikimedia Commons has media related to Erinaceinae.

• Hedgehogs (Species) at Curlie
• Hedgehog reference at the University of Michigan Museum of Zoology
• Natural History of European Hedgehogs (Wildlife Online)
• "Hedgehog" . Encyclopedia Americana. 1920.