Hedgehog in the context of "Hedgehog signaling pathway"

A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia (/məˈmeɪli.ə/). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,640 extant species of mammals have been described and divided into 27 orders. The study of mammals is called mammalogy.

The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the even-toed ungulates (including pigs, bovids and whales), and the Carnivora (including cats, dogs, and seals).

Paubrasilia echinata is a species of flowering plant in the legume family, Fabaceae, that is endemic to the Atlantic Forest of Brazil. It is a Brazilian timber tree commonly known as brazilwood (pau-brasil; Tupi: ybyrapytanga) and is the national tree of Brazil. This plant has a dense, orange-red heartwood that takes a high shine, and it is the premier wood used for making bows for stringed instruments. The wood also yields a historically important red dye called brazilin, which oxidizes to brazilein.

The name pau-brasil was applied to certain species of the genus Caesalpinia in the medieval period, and was given its original scientific name Caesalpinia echinata in 1785 by Jean-Baptiste Lamarck. More recent taxonomic studies have suggested that it merits recognition as a separate genus, and it was thus renamed Paubrasilia echinata in 2016. The Latin specific epithet of echinata refers to hedgehog, from echinus, and describes the thorns which cover all parts of the tree (including the fruits).

Eulipotyphla (/ˌjuːlɪpoʊˈtɪflə/, from eu- + Lipotyphla, meaning truly lacking blind gut; sometimes called true insectivores) is an order of mammals comprising the families Erinaceidae (hedgehogs and gymnures), Solenodontidae (solenodons), Talpidae (moles, shrew-like moles and desmans), and Soricidae (true shrews).

Echidnas (/ɪˈkɪdnəz/), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae /tækiˈɡlɒsɪdiː/, living in Australia and New Guinea. The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the only surviving members of the order Monotremata. The diet of some species consists of ants and termites, but they are not closely related to the American true anteaters or to hedgehogs. Their young are called puggles.

Echidnas evolved between 20 and 50 million years ago and descend from an amphibious, platypus-like monotreme.

A tenrec (/ˈtɛnrɛk/) is a mammal belonging to any species within the afrotherian family Tenrecidae, which is endemic to Madagascar. Tenrecs are a very diverse group, as a result of adaptive radiation, and exhibit convergent evolution; some resemble hedgehogs, shrews, opossums, rats, or mice. They occupy aquatic, arboreal, terrestrial, and fossorial environments. Some of these species, including the greater hedgehog tenrec, can be found in the Madagascar dry deciduous forests. However, the speciation rate in this group has been higher in humid forests.

All tenrecs are believed to descend from a common ancestor that lived 29–37 million years ago after rafting over from Africa. The split from their closest relatives, African otter shrews, is estimated to have occurred about 47–53 million years ago.

Erinaceidae /ˌɛrɪnəˈsiːɪdiː/ (from Latin erinaceus, "hedgehog") is a family in the order Eulipotyphla, consisting of the hedgehogs and moonrats. Until recently, it was assigned to the order Erinaceomorpha, which has been subsumed with the paraphyletic Soricomorpha into Eulipotyphla. Eulipotyphla has been shown to be monophyletic; Soricomorpha is paraphyletic because both Soricidae and Talpidae share a more recent common ancestor with Erinaceidae than with solenodons.

Erinaceidae contains the well-known hedgehogs (subfamily Erinaceinae) of Eurasia and Africa and the gymnures or moonrats (subfamily Galericinae) of Southeast Asia. This family was once considered part of the order Insectivora, but that polyphyletic order is now considered defunct.

Gymnures, also called hairy hedgehogs or moonrats, are mammals belonging to the subfamily Galericinae, in the family Erinaceidae and the order Eulipotyphla. Gymnures may resemble rats but are not closely related; they are not rodents at all, but instead are closely related to hedgehogs, being their sister group within Erinaceidae. They are thought to have appeared in Eastern Asia before their closest relatives, and changed little from the original ancestor, which is thought to have been also the ancestor of the shrews.

Amphechinus is an extinct genus of hedgehog of the family Erinaceidae, which lived in Asia and Europe during the Oligocene and in North America, Africa, Asia and Europe during the Miocene. The genus contains at least 14 species. It is classified in the subfamily Erinaceinae and in the family Erinaceidae.

A single specimen examined in 1998 was estimated to have had a weight of 175 g (0.39 lb) when alive.