Insectivora

Insectivora [in‚sek′tiv·ə·rə]

(vertebrate zoology)

An order of mammals including hedgehogs, shrews, moles, and other forms, most of which have spines.

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Insectivora

An order of placental mammals including shrews, moles, and hedgehogs. The tree shrews (Tupaiidae) and elephant shrews (Macroscelididae) are now recognized as unrelated, and they are placed in separate orders (Scandentia and Macroscelidea). Formerly thought to be the basal placental order, from which other orders were derived, the Insectivora is now restricted to members of the former suborder Lipotyphla. It evolved side by side with the other placental orders, with a fossil record going back to the Paleocene. A number of fossil families from the Cretaceous and early Tertiary, formerly included in the Insectivora, are classified as Proteutheria.

Living lipotyphlous insectivores are small animals: the largest (Potamogale) weighs about 1 kg (2 lb). Most eat insects, worms, and other invertebrates, for which they search in ground litter and vegetation, using their highly developed olfactory sense and their mobile, sensitive snouts. Some burrow, such as moles; some are aquatic, such as the desman. Anatomically, they are distinguished by the absense of a cecum on the intestine, reduction of the pubic symphysis (fibrocartilaginous union of bones), and characters of the skull. The cheek teeth typically have sharp cusps and crests, and the incisors are often enlarged to act as forceps. Insectivores are found on all continents except Australia and Antarctica, but only one genus (Cryptotis, a shrew) has reached South America.

Three suborders can be distinguished: Erinaceomorpha, Soricomorpha, and Chrysochloromorpha. Living erinaceomorphs belong to the family Erinaceidae, comprising the spiny hedgehogs (Erinaceinae) of Eurasia and Africa and the hairy moonrats (Echinosoricinae) of Southeast Asia.

Four living families are included in the Soricomorpha: Soricidae (shrews), Talpidae (moles, desman), Tenrecidae (Madagascan tenrecs and African otter shrews), and Solenodontidae (Solenodon, confined to Cuba and Hispaniola). Among the talpids, the subfamily Talpinae is the most advanced in modification of the forelimbs for burrowing, the Desmaninae have aquatic adaptations, and the Uropsilinae (represented by the Chinese shrew mole) retained shrewlike limbs. True moles did not reach North America until the Miocene; they were preceded in the Oligocene by the Proscalopidae, which burrowed in a different way, with the hands moving longitudinally beneath the body, instead of laterally as in true moles. The living Solenodon, in the West Indies, is one of the largest insectivores, but nevertheless shrewlike. The Tenrecidae are far removed geographically from other soricomorphs. They probably evolved in Africa, where their fossil history goes back to the early Miocene, and the otter shrews (Potamogalinae) survive on the continent of Africa today. The remainder are in Madagascar where, like the lemurs, they have evolved in diverse directions during a long time of isolation. In some ways, for example brain size, they have remained more primitive than other insectivores.

The golden moles (Chrysochloridae) are put into a separate suborder, Chrysochloromorpha. They are highly specialized burrowers, using large claws on the forefoot. They are confined to Africa, where fossils show that they were already specialized in the early Miocene. See Mammalia