Editing Hedgehog (section)

==Description==
Hedgehogs are easily recognized by their [[Spine (zoology)|spines]], which are hollow hairs made stiff with [[keratin]].<ref name=Attenborough>{{cite AV media | author=Attenborough, David | title=Attenborough's Natural Curiosities 2 | volume=Armoured Animals | year=2014 | publisher=UKTV}}</ref> Their spines are not [[poison]]ous or [[wikt:barb|barb]]ed 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]].

[[File:cmglee Horniman hedgehog skin skeleton.jpg|thumb|A skin-skeletal preparation]]
[[File:Hedgehog sting in SEM, 20x en.GIF|thumb|Close-up of the last {{convert|5|mm}} of a hedgehog spine ([[scanning electron microscope|SEM]] microscopy)]]
[[File:Hedgehog in Jurmala.jpg|thumb|right|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.<ref name=Attenborough/> 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 [[hibernation|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 [[self-anointing in animals|anointing]].<ref name="National Wildlife 1 June 2005">{{cite news |last= Drew |first= Lisa W. |title= Meet the Hedgehog: What feeds on lizards, chews venomous toad skins and coats its spiky body with frothy saliva? |url= https://www.nwf.org/News-and-Magazines/National-Wildlife/Animals/Archives/2005/Meet-the-Hedgehog.aspx |date= 1 June 2005 |work= [[National Wildlife]] |location= [[Reston, Virginia]] |publisher= [[National Wildlife Federation]] |access-date= 12 July 2017 |archive-date= 14 September 2015 |archive-url= https://web.archive.org/web/20150914231116/http://www.nwf.org/News-and-Magazines/National-Wildlife/Animals/Archives/2005/Meet-the-Hedgehog.aspx |url-status= live }}</ref> 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 [[Spine (zoology)|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 (bird activity)|anting]] after a similar behavior in birds.

Like [[opossums]], mice, and [[mole (animal)|moles]], hedgehogs have some natural [[Snake venom#Immunity|immunity]] against some [[snake venom]] through the protein [[erinacin]] in their muscles, though in such small amounts that a [[Viperidae|viper]] bite may still be fatal.<ref>{{cite journal |first=Tamotsu |last=Omori-Satoha |author2=Yoshio Yamakawab |author3=Dietrich Mebs |title=The antihemorrhagic factor, erinacin, from the European hedgehog (Erinaceus europaeus), a metalloprotease inhibitor of large molecular size possessing ficolin/opsonin P35 lectin domains |journal=Toxicon |volume=38 |issue=11 |pages=1561–80 |date=November 2000 |pmid=10775756 |doi=10.1016/S0041-0101(00)00090-8 |bibcode=2000Txcn...38.1561O }}</ref> In addition, hedgehogs are one of four known mammalian groups with natural protection against another snake venom, [[Snake venom#Neurotoxins|α-neurotoxin]]. Developing independently, [[Wild boar|pig]]s, [[honey badger]]s, [[mongoose]]s, and hedgehogs all have mutations in the [[nicotinic acetylcholine receptor]] that prevent the binding of the [[snake venom]] α-[[neurotoxin]].<ref>{{cite journal|last1=Drabeck|first1=D.H.|last2=Dean|first2=A.M.|last3=Jansa|first3=S.A.|title=Why the honey badger don't care: Convergent evolution of venom-targeted nicotinic acetylcholine receptors in mammals that survive venomous snake bites|journal=Toxicon|date=1 June 2015|volume=99|pages=68–72|doi=10.1016/j.toxicon.2015.03.007|pmid=25796346|bibcode=2015Txcn...99...68D }}</ref>

The [[Olfactory system|sense of smell]] has been little studied in the hedgehog, as the olfactory part of the mammal brain is obscured inside the [[Neocortex|neopallium]]. Tests have suggested that hedgehogs share the same olfactory electrical activity as cats.<ref>{{Cite journal |title = Olfactory reactions in the brain of the hedgehog|date = 1942 |journal = The Journal of Physiology |volume= 100 |issue = 4|pages= 459–473 |last = Adrian|first = E. D.|doi = 10.1113/jphysiol.1942.sp003955|pmid = 16991539|pmc = 1393326}}</ref>