Search Results

Most commonly, a generic name for all fossil resins, although it has been restricted by some to refer only to succinite, the mineralogical species of fossil resin that includes most of the Baltic Coast deposits. The time necessary to transform resin…

An ongoing current event in which a large number of living species are threatened with extinction or are going extinct because of environmentally destructive human activities. The Earth is presently in the midst of a mass extinction event. In the…

Any of several leguminous plants, or their seeds, long utilized as food by humans or livestock. There are more than 40,000 varieties of beans, with only a small number of these being mass-produced for human or animal consumption. In particular,…

Any member of the grass family (Poaceae or Gramineae) that produces edible grains usable as food by humans and livestock. Cereals are important cultivated crops. Common cereals include rice, wheat, barley, oats, maize (corn), sorghum, rye, and…

The response of corals to environmental stress in which they eject the single-cell algae that live within the transparent coral tissue, making the white coral skeleton visible. Corals (Fig. 1) are animals that live in a partnership (symbiosis) with…

A species translocated from one region or continent to another outside its normal range, particularly when the translocation is the result of human activity (intentional or otherwise). Many thousands of species, including animals, plants, fungi,…

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 natural process in which harmful or beneficial effects are caused by secondary metabolites that spread from a donor organism to a recipient and are produced by plants, algae, bacteria, and fungi. Allelopathy is a key ecological process and has…

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…

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…

Vegetables that are prevalent in Asian cuisines, but less well known in Western diets. Asian vegetables (Fig. 1), also referred to as Asian greens or oriental vegetables, are very important in Asian countries, but are not as popular in North America…

A white, crystalline compound, 1-aspartyl-1-phenylalanine methyl ester (APM), used as an artificial sweetener. Aspartame is composed of two amino acids: aspartic acid and phenylalanine [structure (1)]. Amino acid Artificial sweetener Aspartame…

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…

A fermented beverage produced from grain. Beer is a generic term used to describe alcoholic beverages made from cereal grains, especially barley (Fig. 1), in the form of malt. Ale, lager, porter, and stout are different kinds of beer made by…

The study of behavior change in response to drugs, chemicals, or other environmental conditions or agents. Behavioral toxicology investigates the effect of toxic exposure on organismal behavior. The toxic exposure can involve various chemicals,…

The destruction of organic compounds by microorganisms. Biodegradation is a process (carried out by microorganisms) that decomposes organic material into its constituent elements or new compounds. Microorganisms, particularly bacteria (and fungi to…

A microbial (often bacterial) community that is enveloped by an adhesive substance (the glycocalyx) at the interface of a liquid and a surface. Biofilms (see illustration) are defined as highly structured communities of microorganisms that are…

The study of the cycling of chemicals between organisms and the surface environment of the Earth. The chemicals either can be taken up by organisms and used for growth and synthesis of living matter or can be processed to obtain energy. The chemical…

The use of parasitoids, predators, and pathogens to reduce injurious pest insect populations and consequently the damage that they cause. Biological insect control (or insect biocontrol) is the regulation of insect populations by biological means.…

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,…

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…

Products derived from the seeds of the tropical tree Theobroma cacao. The cacao tree (Fig. 1) grows within a narrow belt along both sides of the Equator. There are three basic varieties: Criollo, which was native to Central and South America;…

Keeping perishable products at low temperatures to extend shelf life. Cold storage vastly retards the natural deterioration of perishable products at higher temperatures. Time and temperature are the key factors that determine how well foods (see…

Management of the human use of natural resources to provide the maximum benefit to current generations while maintaining capacity to meet the needs of future generations. Conservation includes both the protection and rational use of natural…

Pathological conditions affecting the health of coral and causing its physiological dysfunction. Broadly defined, coral disease (Fig. 1) is any impairment to coral health resulting in physiological disturbance and breakdown. It usually involves…

A measure of the three-dimensional structure of live coral communities on reefs. Coral reef structural complexity is an intrinsic element of coral reef ecosystems and quantitates the surface area of coral in relation to its linear area. The…

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…

Equipment used in the production and processing of milk and milk products, including milking machines, cream separators, coolers, pasteurizers, homogenizers, butter-making equipment, evaporators and dryers, and related items of equipment. Dairy…

The term (meaning terrible lizards) assigned to a group of certain large, ancient bipedal and quadrupedal reptiles that lived during the Mesozoic Era. The term Dinosauria [from the Greek deinos (fearful or terrible) and sauros (reptile or lizard)]…

Potable alcoholic beverages, each obtained by distilling an alcohol-containing liquid and further treating the distillate to obtain a beverage of specific character. Classification The various distilled spirits are classified according to (1) the…

Plants occupying sand dunes and the slacks, or swales, and flats between them. The density and diversity of dune vegetation are greater on coastal dunes than on desert dunes. Dune Plant geography Sand Zonation A zonation pattern is evident in the…

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…

The biological sonar that bats, toothed whales, and certain other animals use to navigate without the visual system. Echolocation, or biosonar, is the physiological process that certain animals use to locate objects by reflected sound, primarily in…

The interaction of at least two organisms or species such that, for each, the birth or growth rates are depressed and the death rate increased by the presence of the other organisms or species. Ecological competition is the conflict that arises…

The study of the flow of energy within an ecological system from the time the energy enters the living system until it is ultimately degraded to heat and irretrievably lost from the system. It is also referred to as production ecology, because…

The methods required for the measurement of features of plant and animal populations or for quantifying energy flow or other aspects of ecological communities. Ecologists are concerned with such a wide range of variables that they may use many other…

The use of computer simulations or mathematical equations to address questions that cannot be answered solely by experiments or observations. Ecological models have two major aims: to provide general insight into how ecological systems or ecological…

A directional change in an ecological community. Populations of animals and plants are in a dynamic state. Through the continual turnover of individuals, a population may expand or decline depending on the success of its members in survival and…

The study of insects that have a direct influence on humanity. Though this includes beneficial as well as harmful species, most attention is devoted to the latter and how they become pests and are controlled. The emphasis on managing harmful insects…

An obligate association formed between the roots of many plant species, especially trees, and a diverse range of soil fungi. The fungi and the finest, terminal root tips interact to form joint organs called ectomycorrhizas (Fig. 1). 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 sum of all external factors, both biotic (living) and abiotic (nonliving), to which an organism is exposed. All of the outside factors to which an organism is exposed comprise its environment (Fig. 1). The environment has a tremendous influence…

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…

The death and disappearance of a species. The fossil record shows that extinctions have been occurring throughout the history of life. Mass extinctions refer to the loss of a large number of species representing broad taxonomic, ecologic, and…

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…