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
Domain:	Eukaryota
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] Another name that is used is hedgepig.^[5]

Description

Hedgehogs are easily recognized by their spines, which are hollow hairs made stiff with keratin.^[6] 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.

Hedgehogs roll into a tight spiny ball when threatened, tucking in the furry face, feet, and belly.^[6] The hedgehog's back contains two large muscles that direct the quills. Some light-weight desert hedgehog species with fewer spines are more likely to flee or attack, ramming an intruder with the spines, rolling up only as a last resort.

Hedgehogs are primarily nocturnal, with some species also active during the day. Hedgehogs sleep for a large portion of the day under bushes, grasses, rocks, or most commonly in dens dug underground. All wild hedgehogs can hibernate, though the duration depends on temperature, species, and abundance of food.

Hedgehogs are fairly vocal, with a variety of grunts, snuffles and/or squeals.

They occasionally perform a ritual called anointing.^[7] 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. Some experts believe this might serve to camouflage the hedgehog with the local scent, and might also lead to infection of predators poked by the spines. Anointing is sometimes also called anting after a similar behavior in birds.

Like opossums, mice, and moles, hedgehogs have some natural immunity against some snake venom through the protein erinacin in their muscles, though in such small amounts that a viper bite may still be fatal.^[8] In addition, hedgehogs are one of four known mammalian groups with natural protection against another snake venom, α-neurotoxin. Developing independently, pigs, honey badgers, mongooses, and hedgehogs all have mutations in the nicotinic acetylcholine receptor that prevent the binding of the snake venom α-neurotoxin.^[9]

The sense of smell has been little studied in the hedgehog, as the olfactory part of the mammal brain is obscured inside the neopallium. Tests have suggested that hedgehogs share the same olfactory electrical activity as cats.^[10]

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, and melons.^[6] Afghan hedgehogs devour berries in early spring after hibernation.^{[citation needed]} Hedgehogs have been observed eating cat food left outdoors for pets, but this may not be a proper food for hedgehogs in captivity.[video:1]

Hibernation

When a hedgehog hibernates, its normal 30–35 °C (86–95 °F) body temperature decreases to 2–5 °C (36–41 °F).^[11]

Reproduction and lifespan

Hedgehog gestation lasts 35–58 days, depending on species. 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. In captivity, lack of predators and controlled diet contribute to a lifespan of 8–10 years depending on size. In the wild, larger species live 4–7 years (some recorded up to 16 years), and smaller species live 2–4 years (4–7 in captivity). This compares to a mouse at 2 years and a large rat at 3–5 years.

Newborn hoglets are blind, with their quills covered by a protective membrane which dries and shrinks over several hours,^[12] and falls off after cleaning, allowing the quills to emerge.^[13]

Predators

The various species have many 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 Eurasian eagle owl.^[14]

In Britain, the main predator is the European badger. European hedgehog populations in the United Kingdom are lower in areas with many badgers,^[15] and hedgehog rescue societies will not release hedgehogs into known badger territories.^[16] Badgers also compete with hedgehogs for food.^[17]

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 smaller North African hedgehog (A. algirus, pygmy hedgehog).^[18] 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,^[19] 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.^[20]

As invasive species

In areas where hedgehogs have been introduced, such as New Zealand and the islands of Scotland, the hedgehog has become a pest, lacking natural predators. In New Zealand it has decimated native species including insects, snails, lizards and ground-nesting birds, particularly shore birds.^[21]

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 protest. Eradication began in 2003 with 690 hedgehogs killed, though animal welfare groups attempted rescues. By 2007, legal injunctions prohibited the killing, and in 2008, the elimination process was changed to trapping and releasing on the mainland.^[22]

In 2022, it was reported that the hedgehog population in rural Britain declining rapidly, down by 30%-75% since 2000.^[23]

Diseases

Hedgehogs suffer many diseases common to mammals,^[24] including cancer, fatty liver disease, and cardiovascular disease.

Cancer is very common in hedgehogs. The most common is squamous cell carcinoma, which spreads quickly from bone to the organs, unlike in humans. Surgery to remove the bone tumors is impractical.

Fatty liver and heart disease are believed to be caused by bad diet and obesity. Hedgehogs will eagerly eat foods high in fat and sugar, despite a metabolism adapted for low-fat, protein-rich insects.

Hedgehogs are also highly susceptible to pneumonia, with difficulty breathing and nasal discharge,^[25] caused by the bacterium Bordetella bronchiseptica.^[26]

Hedgehogs uncommonly transmit a fungal ringworm or dermatophytosis skin infection to human handlers and other hedgehogs, caused by Trichophyton erinacei, a distinct mating group among the Arthroderma benhamiae fungi.^[27]

 

Hedgehog suffering from balloon syndrome before deflating

Hedgehogs can suffer from balloon syndrome, a rare condition in which gas is trapped under the skin from injury or infection, causing the animal to inflate. The condition is unique to hedgehogs because their skin is baggy enough to curl up.^[28] In 2017 the BBC reported a case of a male hedgehog "almost twice its natural size, literally blown up like a beach ball with incredibly taut skin".^[29][30] At Stapeley's Wildlife Hospital, vet Bev Panto, said, "I have seen three or four of these cases and they are very strange every time and quite shocking ... When you first see them they appear to be very big hedgehogs but when you pick them up they feel so light because they are mostly air".^[28] The British Hedgehog Preservation Society advises:

There is no single cause for this condition. The air can be removed by incising or aspirating through the skin over the back. Antibiotic cover should be given. This may be associated with lung/chest wall damage or a small external wound acting like a valve or a clostridium type infection.^[31]

Human influence

As with most small mammals living around humans, 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.^[32]

Domesticated hedgehogs can get their heads stuck in tubes such as toilet paper tubes, and walk around with them. Some owners call this "tubing" and promote the behavior, providing a tube cut lengthwise to allow the hedgehog to remove it. Some hedgehogs intentionally wear tubes for hours.^[33]

Culinary and medicinal use

Hedgehogs are a food source in many cultures. They were eaten in Ancient Egypt and some recipes of the Late Middle Ages call for hedgehog meat.^[34] They are traded throughout Eurasia and Africa for traditional medicine and witchcraft. In the Middle East and especially among Bedouins, hedgehog meat is considered medicine against rheumatism and arthritis.^[35] Hedgehogs are also said to cure a variety of disorders from tuberculosis to impotence. In Morocco, inhaling the smoke of the burnt skin or bristles supposedly remedies fever, 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.^[36] Romani people still eat hedgehogs, boiled or roasted, and also use the blood and the fat as a medicine.^[37]

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.^[38][39] As they did not contain any actual hedgehog product, the Office of Fair Trading ordered him to change the name to Hedgehog Flavour Crisps.^[40]

•  
  Hedgehog amulet from Ancient Egypt, New Kingdom, Dynasty 18. Steatite. Cleveland Museum of Art. 1391 BCE to 1353 BCE
•  
  Ceramic rhyton in the form of a hedgehog. Mycenaean. 14th to 13th century BCE
•  
  Hedgehog sculpture. Faience. Ancient Egypt, Thebes. 1991 BCE to 1778 BCE

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

• Hedgehogs in culture
• The Hedgehog and the Fox
• Echidnas or "spiny anteaters" of order Monotremata (egg-laying mammals)
• Porcupines, two rodent families with spines or quills
• Lesser hedgehog tenrec
• Greater hedgehog tenrec
• Hedgehog's dilemma

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. "Definition of HEDGEPIG". www.merriam-webster.com. Retrieved 31 January 2024.
6. Attenborough, David (2014). Attenborough's Natural Curiosities 2. Vol. Armoured Animals. UKTV.
7. 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. from the original on 14 September 2015. Retrieved 12 July 2017.
8. 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.
9. 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.
10. 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.
11. 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.
12. Litter – Burlington and MIDI (2004-04-19) 10 July 2009 at the Wayback Machine. hamorhollow.com
13. . Hedghogz.co.uk. Archived from the original on 6 September 2013. Retrieved 8 March 2009.
14. . wildlifeinformation.org
15. 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
16. Where have all the hedgehogs gone ? 17 June 2018 at the Wayback Machine. Snufflelodge.org.uk. Retrieved 2013-09-05.
17. David Wembridge. "The State of Britain's Hedgehogs 2011" (PDF). The British Hedgehog Preservation Society. (PDF) from the original on 18 May 2013.
18. "The Complete Guide to Hedgehogs". www.petmd.com. from the original on 16 February 2020. Retrieved 16 February 2020.
19. 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.
20. . Corpo Forestale dello Stato. Archived from the original on 2 November 2016. Retrieved 31 August 2014.
21. . Landcare Research media release. 17 September 2003. Archived from the original on 1 October 2003. Retrieved 6 December 2011.
22. Ross, David (14 January 2009). "18 Trappers Sought for Hebrides to Protect Birds from Hedgehogs". The Herald. from the original on 10 August 2011. Retrieved 12 June 2009.
23. "Hedgehog population plummets in UK countryside, research suggests". BBC News. 22 February 2022. from the original on 22 February 2022. Retrieved 22 February 2022.
24. . Wildlifeinformation.org. Archived from the original on 26 July 2010. Retrieved 8 March 2009.
25. "Hedgehogs - Diseases". vca_corporate. from the original on 24 November 2020. Retrieved 2 November 2020.
26. . Bowmanville Veterinary Clinic. Archived from the original on 6 November 2020. Retrieved 2 November 2020.
27. 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.
28. Staff writer(s) (12 June 2017). "Balloon syndrome hedgehog is 'popped'". BBC News Online. BBC. Retrieved 12 June 2017.
29. "Hedgehog 'blown up like beach ball' has balloon syndrome". BBC News Online. BBC. 11 June 2017. Retrieved 11 June 2017.
30. Staff writer(s) (22 May 2013). "Inflated 'balloon' hedgehog saved from 'rupturing' by vet". BBC News Online. BBC. Retrieved 11 June 2017.
31. Forshaw, Hugh. "' Care and Treatment of Sick and Injured Hedgehogs" (PDF). britishhedgehogs.org.uk. British Hedgehog Preservation Society. (PDF) from the original on 12 April 2013. Retrieved 11 June 2017.
32. 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.
33. . Hedgehog World. Archived from the original on 15 January 2008. Retrieved 8 March 2009.
34. Pidd, Helen (14 September 2007). "Roast hedgehog and nettle pud – a slap-up feast for ancient Britons". The Guardian. London. from the original on 28 May 2020. Retrieved 12 June 2009.
35. Qumsiyeh, Mazin B. (1996). Mammals of the Holy Land. Texas Tech UP. p. 64. ISBN 978-0-89672-364-1.
36. 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.
37. Wood, Manfri Frederick (1979). In the Life of a Romany Gypsy. J.A. Brune. pp. 80–81. ISBN 978-0-7100-0197-9. from the original on 10 February 2023. Retrieved 28 February 2021.
38. 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. from the original on 10 February 2023. Retrieved 22 July 2022.
39. "Hedgehog Crisps' Welshpool inventor dies, aged 74". Shropshire Star. 28 February 2017. from the original on 20 June 2021. Retrieved 7 August 2021.
40. "Hedgehog Crisps' Welshpool inventor dies, aged 74". Shropshire Star. 28 February 2017. from the original on 27 October 2021. Retrieved 15 September 2021.

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.