By DJANI Wildlife Projects on Dec 21, 2009 | In ENGLISH
Although their basic body plan is sometimes described as very primitive, hedgehogs are equipped with some of the most fascinating and ingenuous adaptations of which the most obvious are its spiny coat and ability to roll itself into a perfect ball. An adult has about 5 000 needle sharp spines of 2 – 3 cm long covering the skin from the forehead, around the back of the ears, the whole upper parts of the body, excluding only the face, limbs and tail which are covered with hair. The spines are modified hairs and to keep each spine strong but light in weight, it is filled with numerous small air-filled chambers separated by thin partitions. Each spine narrows to a thin flexible neck towards its base and then widens to form a small ball, which is embedded in the skin. This unique construction ensures that the thin flexible part bends on impact, rather than sending the base of the spine into the hedgehog’s own body when attacked, bumping the body or when falling.
A small muscle at the base of each spine controls its movement, on contraction the spine is erected and when relaxed, the spine will lie flat against the skin. Erected spines criss-cross over one another, forming an almost impenetrable barrier, especially when the animal is curled up in a ball. The latter is made possible by its oversized skin and an underlying powerful muscle layer covering the back. This muscle layer is very loosely connected to the body beneath and when contracted, its thicker and more powerful edges form a circular muscle band that acts like the drawstring around the opening of a bag, forcing the content deeper as it is drawn tighter. As the skin is pulled tightly over the body, the spines are automatically erected but at no stage ejected. Hedgehogs often smear their spines with copious foamy saliva, which may either act as a sexual attractant, to further deter predators with its strong odour and bad taste, or to reduce parasites. Although hedgehogs are known to carry large amounts of parasites such as ticks, fleas and ringworm, among their spines, these parasites tend to be hedgehog specific and are not easily transmitted to humans or other animal species.
South African hedgehogs usually occur alone, in pairs or small groups consisting of females with their young. They are mainly insectivores and nocturnal but may be active during daylight, especially after rain when insects and earthworms tend to be out and in the open. When foraging, they move slowly, locating prey among debris or below the soil surface by using their keen sense of smell and hearing. If alarmed, these spiny creatures can run surprisingly fast. Apart from invertebrates, they will also consume frogs, lizards, eggs, chicks, fruit, seeds and other plant material. Apparently they are independent of drinking water. To save energy during winter and times of food shortage, they are able to hibernate. Mating is usually a noisy affair with lots of snorting. The female flattens the spines on her back while the male grasp the spines on her shoulder in his teeth to prevent himself from slipping backwards. To further “smoothen” the process, the female’s vaginal opening is placed far back while the male’s elongated penis is situated far forwardly. Babies are born in a nest, naked with spines but eyes and ears closed. However, the spines lie just beneath the skin, which is engorged with large amounts of fluid to avoid injuring the mother during birth.
OTHER NAMES: Hedgehog; Suid-Afrikaanse krimpvarkie; Krimpvarkie; Hérisson d’Afrique du Sad; Südafrikanischer Igel; Shoni; Thlong; Umahau; Thoni; Inhloni.
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