Glossary: E

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

../images/worldmap.2001.jpg

echinopluteus larva

the larva of echinoids (sea urchins, sand dollars, and heart urchins), Class Echinoidea, Phylum Echinodemata.

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

ecological extinction

The reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species.

ecologist

A scientist who studies how living things (plants and animals) interact with each other and their physical environment.

ecology

The study of the interrelationships among plants, animals and other organisms and their interaction with all aspects of their natural environment.

ecosystem

A space which includes living things that interact with each other and their physical environment.

  1. ...the more fundamental conception is ... the whole system ..., including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment of the biome - the habitat factors in the widest sense. It is the systems so formed which, from the point of view of the ecologist, are the basic units of nature on the face of the earth. These ecosystems, as we may call them, are of the most various kinds and sizes... (Introduction and definition of a new term, ecosystem, by Alfred Tansley in 1935) 2. All the individuals, species and populations in a spatially defined area, the interactions among them, and those between the organisms and the abiotic environment.
ecosystem functioning

The sum total of processes operating at the ecosystem level, such as the cycling of matter, energy and nutrients, as well as those processes operating at lower ecological levels which impact on patterns or processes at the ecosystem level (e.g. interactions among species or the transfer of genetic material).

ecosystem roles and associations

the roles this species plays in its ecosystem. How does it affect other species? What other species does it have close interactions with?

ecotone

A transition between two or more different habitats; e.g. between forest and grassland.

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

ecotype

A genetically induced variety within a single species, adapted for local ecological conditions.

ectoderm

the outermost of the three germ layers of an animal embryo. Ectoderm gives rise to the skin, nervous system, and the adrenal medulla.

ectoparasite

a parasite that lives on the outside of its host's body.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

edaphic

Influenced by the soil rather than the climate.

edentate

A member of an order comprising living and extinct anteaters, armadillos, pangolins, and sloths.

effective population size

The average number of individuals in a population that actually contribute genes to succeeding generations.

electric

uses electric signals to communicate

elevation

height above sea level

embryonic diapause

At about the time a female gives birth (e.g. in most kangaroo species), she also becomes receptive and mates. Embryos produced at this mating develop only as far as a hollow ball of cells (the blastocyst) and then become quiescent, entering a state of suspended animation or embryonic diapause. The hormonal signal (prolactin) which blocks further development of the blastocyst is produced in response to the sucking stimulus from the young in the pouch. When sucking decreases as the young begins to eat other food and to leave the pouch, or if the young is lost from the pouch, the quiescent blastocyst resumes development, the embryo is born, and the cycle begins again. (Macdonald 1984)

endemic

in referring to a particular group (taxon), restricted to a specific location or region.

endoderm

the outermost of the three germ layers of an animal embryo. Endoderm gives rise to the alimentary canal and the digestive glands of the adult.

endoskeleton

Mineral support within the body. Synapomorphy of the Echinodermata.

endostyle

Grooves on the pharyngeal sack of urochordates and hemichordates, containing cilia and thick mucus, which filter food particles from the water siphoned into the pharynx and carry them to the esophagus for digestion. Synapomorphy of the Chordata.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

animals that generate their own body heat through metabolic processes.

enterocoely

Type of development whereby the coelom and mesoderm form as an evagination of the archenteron wall, thus are derived from the endodermal epithelium. Synapomorphy of the Deuterostomia.

enzootic

A disease that is persistently found in an animal population (compare Epizootic).

epidermis

the external cellular layer of a multicellular organism. Invertebrate epidermis is often one cell thick and may secrete a waxy cuticle. Vertebrate epidermis is the multiple cell layer of the skin.

the outermost cell layer of a multicellular organism, an example is the skin of vertebrates.

epiphytic

Referring to a plant that lives on the surface of another plant, typically a tree, or other structure and obtains its moisture and nutrients from the air and rain.

epizootic

A disease outbreak in an animal population that occurs at a particular time and does not persist (compare Enzootic).

equids

members of the mammalian family Equidae, including horses, asses, and zebras.

erg

An Arabic term for the great sand deserts, or sand seas, of the Sahara Desert (actually, the term erg in Arabic means a vein or belt). An erg can be as large as France, covering well over 260,000 sq km (100,000 sq mi). An erg consists mostly of sand, shaped by the wind into dunes, and it may contain salt flats and the exposed gravel surface of the desert floor. (Langewiesche 1996)

escarpment

A long cliff separating two relatively level or gently sloping surfaces.

estrus

The period in the estrus cycle of a female mammal when she is usually attractive to males and receptive to mating.

estrus cycle

In female mammals (other than most primates), the hormonally controlled, regularly repeated stages by which the body is prepared for reproduction.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

an area where a freshwater river meets the ocean and the fresh and saltwater mixes

eucoelom

A secondary body cavity between the gut and body wall, containing visceral organs and gonads, completely surrounded by mesoderm. Synapomorphy of Onychophora+Tardigrada+Arthropoda. Convergent within Trochozoa and Deuterostomia.

eusocial

the condition in which individuals in a group display each of the following three traits: cooperative care of young; some individuals in the group give up reproduction and specialize in care of young; overlap of at least two generations of life stages capable of contributing to colony labor

eutaxic

refers to the presence of a fifth secondary feather in birds. Also used to denote the situation in which there is no gap between the fourth and fifth secondary feather in birds, usually with 9 or 10 primary feathers.

evisceration

to remove the viscera, or internal organs, of an animal.

excretory

describes the act of expelling waste matter from an animal.

exoskeleton

A hard supporting structure on the outside of the body, enclosing all living cells (external skeleton).

exotic species

Introduced, non-native species.

external fertilization

fertilization takes place outside the female's body

extirpate

the extermination of a population of a species from a given area.