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A taxonomic order of insects comprising the cockroaches and termites. The order Blattodea, also referred to as Blattaria, contains at least 4500 species of cockroaches (Fig. 1) and 3000 species of termites. Previously, termites were assigned to a…

The common name for three living species of mammals in the family Elephantidae (order Proboscidea). Elephants are extant members of the mammalian family Elephantidae, which is one of several families included in the order Proboscidea., The remaining…

A mammalian order containing the egg-laying platypus and echidnas. Members of the order Monotremata (monotremes) are egg-laying mammals belonging to the subclass Prototheria (in some alternative classifications, the monotremes have been assigned to…

An order of placental mammals containing the largest and most powerful living terrestrial mammals—the elephants. Proboscideans once had a wide distribution, reaching every continent except Australia and Antarctica. Although early forms lacked both…

A nocturnal, burrowing, insectivorous, piglike mammal (Orycteropus afer) in the order Tubulidentata. The mammalian order Tubulidentata contains a single family, Orycteropodidae, and a single extant aardvark species, Orycteropus afer (Fig. 1).…

One of the major classes composing the superclass Tetrapoda of the subphylum Vertebrata, and including frogs, toads, salamanders, and caecilians. Amphibians, that is, members of the class Amphibia, are tetrapod vertebrates. Modern amphibians number…

Any living organism taxonomically assigned to the classification kingdom known as Animalia. Members of the kingdom Animalia—that is, animals (see illustration)—possess certain characteristics that distinguish them from organisms belonging to the…

A discipline within the field of animal behavior that focuses on the reception and use of signals. Animal communication could well include all of animal behavior because a liberal definition of the term signal could encompass all stimuli perceived…

The group of primates most closely related to humans. The primates included in the ape group are the African great apes, the gorillas (Fig. 1) and chimpanzees; the Asian great apes, the orangutans; and the lesser apes from Asia, the gibbons. Humans…

The scientific study of past material culture. The initial objective of archeology (often spelled archaeology) is to construct cultural chronologies that order past material culture into meaningful temporal segments. The intermediate objective is to…

An order of leeches (subclass Hirudinida) characterized by the absence of a protrusible proboscis and including both blood-feeding and macrophagous (predatory) varieties. Most notorious among the blood-feeding leeches in the Arhynchobdellida is the…

A class of the asterozoan group of the phylum Echinodermata, often known as sea stars or starfish. Members of the class Asteroidea, that is, asteroids, are notable echinoderms with a star-shaped body plan (Fig. 1). Unlike members of their sister…

Any member of the mammalian family Ursidae, which contains the largest terrestrial carnivores. The bear family Ursidae comprises a number of carnivorous mammalian species. There are eight extant species of bears in three subfamilies: Ursinae…

The management and maintenance of colonies of honeybees for human purposes. Beekeeping is an ancient art. Although the commonly known honeybee species (Fig. 1) is native to Europe and Africa, humans have transported them to other continents. The…

One of the main extant classes in the phylum Mollusca. Members of the molluscan class Bivalvia (formerly, Pelecypoda) are known commonly as bivalves and include clams, oysters, mussels, and scallops. All bivalves are aquatic, living at all depths of…

An aquatic mammalian order comprising approximately 90 living species of whales, dolphins, and porpoises and their fossil relatives. Like all other mammals, members of the order Cetacea (cetaceans) nurse their young with milk produced by the mother,…

The common name for numerous species of small to medium-sized lizards that comprise the family Chamaeleonidae (also Chamaeleontidae). Chameleons (see illustration) are members of the family Chamaeleonidae (also Chamaeleontidae) in the order Squamata…

An order of the class Reptilia, including the turtles, terrapins, and tortoises; also termed Testudines. The order Chelonia (often referred to as Testudines) comprises one of the oldest groups of reptiles on Earth. Members of the Chelonia…

A large, tawny brown wild cat, Puma concolor (family Felidae), once widespread over most of the Americas; also known as catamount, mountain lion, painter, and puma. The cougar (Puma concolor; see illustration) is a carnivorous member of the family…

An extremely diverse, species-rich group of arthropods that have inhabited marine environments since the beginning of the Cambrian Period. Crustacea is a notable taxon of invertebrates. Common members of the Crustacea, that is, crustaceans, are…

A class of the phylum Cnidaria, comprising the box jellyfish. Members of the Cubozoa are commonly known as box jellyfish or cubozoans. These cnidarian invertebrates are good swimmers, and their distribution is mostly tropical and subtropical. There…

One of the more highly specialized crustacean orders. Members of the order Decapoda, termed decapods, are prominent crustaceans (superorder Eucarida; class Malacostraca; subphylum Crustacea; phylum Arthropoda), including shrimps, crayfish, lobsters,…

The name for any four-legged, hoofed, grazing animal in the mammalian family Cervidae. Deer are ruminant, even-toed ungulates (hoofed mammals) belonging to the order Artiodactyla. As members of the family Cervidae, they also are known as cervids. In…

An order of nematodes in which the variable stoma may or may not be armed with a dorsal tooth that may or may not be opposed by subventral denticles. The variable amphids (anterior sensory receptors) range from reniform to elongate loops to simple…

An order of nematodes in which the taxa are readily recognized by their conspicuous body annulation. The annuli of members of the order Desmoscolecida may be covered with concretion rings, or the cuticle may be ornamented with scales, warts, or…

An order of sea urchins (class Echinoidea) possessing an aulodont Aristotle's lantern (jaw apparatus) with unkeeled teeth that are U-shaped in cross section, and with the apophyses not meeting at the top of the lantern. In Diadematoida, the…

A large group of flukes (parasitic flatworms) within the class Trematoda, with some thousands of described and probably many thousands of not yet described species. The Digenea range from about 0.2 mm (0.008 in.) to over 1 m (3.3 ft) in length. They…

Members of the carnivorous mammalian family Canidae. All breeds of domestic dogs (Fig. 1), the wild dogs, and related species belong to the family Canidae. Despite the various breeds of domestic dogs that are known, the scientific name for all types…

The adaptation of an animal or plant through breeding in captivity to a life intimately associated with and advantageous to humans. Domesticated plants and animals differ genetically and morphologically from their wild counterparts, often in ways…

The earliest representatives of people anatomically similar to living humans that evolved from more archaic humans approximately 150,000–300,000 years ago. The general process by which early modern humans (Homo sapiens) emerged from late archaic…

A fish in the order Anguilliformes (true eels), one of several orders of the superorder Elopomorpha, which share a leptocephalus (a slender, transparent larva with a long narrow) [Fig. 1] stage. The name eel also applies to other fishes similar in…

A peculiar order of silk-spinning, orthopteroid insects, commonly called the embiids or web spinners, which are related to termites. The order Embioptera (also known as Embiidina or Embiodea) comprises about 300–400 described species, which are…

The major subdivision (subclass) of the crustacean class Malacostraca. It comprises three, four, or five Recent superorders: Syncarida, Peracarida, and Eucarida are most commonly included and all that are recognized here. However, some…

A well-defined marine order of the class Crustacea. These planktonic malacostracans are closely allied with, and sometimes included in, the Decapoda. The order contains two families, one with a single species, the other with about 84 species divided…

One of two extant orders of brittle stars, comprising the basket stars and snake stars, in the class Ophiuroidea (phylum Echinodermata). The order Euryalida currently includes approximately 190 valid species worldwide, which represents a little less…

An extinct Paleozoic group of aquatic arthropods, belonging to the subphylum Chelicerata and class Merostomata and thus related to the living marine xiphosurans (horseshoe crabs) and terrestrial arachnids (spiders, scorpions). Although most…

A division (also known as Hemimetabola) of the subclass Pterygota, including those insects that show relatively slight change in body form with growth. They develop through a series of immature forms (nymphs) from hatchling to adult, so that wings…

A worldwide order of diurnal predacious birds without obvious affinities to other orders of birds. They are not closely related to the owls; any similarities between these two orders are the result of convergence. Aves Classification The…

A specialized keratinous outgrowth of the skin, which is a unique characteristic of birds. Feathers are highly complex structures that provide insulation, protection against mechanical damage, protective coloration, and also function significantly…

The name given to any of three carnivorous mammals in the genus Mustela (family Mustelidae); also known as the polecat. There are three species of ferrets, also termed polecats, belonging to the genus Mustela in the family Mustelidae of the order…

A medium-sized, weasel-like, carnivorous mammal (Martes pennanti or Pekania pennanti) classified in the family Mustelidae. Fishers (Martes pennanti or Pekania pennanti) belong to the family Mustelidae (order Carnivora), which also includes weasels,…

A method of dating geological and archeological specimens by counting the radiation-damage tracks produced by spontaneous fission of uranium impurities in minerals and glasses. During fission two fragments of the uranium nucleus fly apart with high…

An extinct subclass of stalked or creeping Crinoidea which includes some 50 Paleozoic genera, ranging from Ordovician to Permian times. A flexible tegmen was present with open ambulacral grooves. One of the five oral plates served as a madreporite.…

An order of Granuloreticulosia in the class Rhizopodea. Foraminiferans are dominantly marine protozoa (single-celled animals), with a secreted or agglutinated shell, or test, enclosing the continually changing ameboid body that characterizes this…

An order of sea stars (Asteroidea) that includes several ecologically important members that are found primarily in cold to temperate water settings. The Forcipulatida (whose members are referred to herein as forcipulates) occur across a broad depth…

Fossil members of the group of primates constituting the apes. Apes and humans are closely related primates in the superfamily Hominoidea. The living hominoids are subdivided into the families Hylobatidae and Hominidae. The hylobatids, or lesser…

Extinct members of the order of mammals to which humans belong. All current classifications divide the living primates (order Primates) into two major groups (suborders) [Fig. 1]: the Strepsirhini (Strepsirrhini) or "lower" primates (lemurs,…

An extinct superfamily of marine organisms in the phylum Protozoa, order Foraminiferida. Fusulinaceans first appeared late in the Mississippian Period, and in the succeeding 100,000,000 years evolved into more than 125 genera and 6000 species before…

An order of fishes containing the cods, codlings, codlets, grenadiers, and hakes. The Gadiformes plus the orders Ophidiiformes (pearfishes, cusk-eels, and brotulas), Batrachoidiformes (toadfishes), and Lophiiformes (anglerfishes), collectively…

A large order of birds containing the gallinaceous, or chickenlike, birds. Members of the order Galliformes are found worldwide, although several of the subgroups have a more limited distribution. Part of the superorder Neognathae, the galliforms…