Animal Info - Glossary E
- 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 density
- Ecological (or "specific") density is the number (or biomass) per unit of
habitat space (available area or volume that can actually be colonized by the population)
(see "Crude density").
- 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.
- The study of the interrelationships among plants, animals and other organisms and their
interaction with all aspects of their natural environmental.
- 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
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
(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).
- A transition between two or more different habitats; e.g. between forest and grassland.
- A genetically induced variety within a single species, adapted for local ecological
- A member of an order comprising living and extinct anteaters, armadillos, pangolins and
- Influenced by the soil rather than the climate.
- Effective population size
- The average number of individuals in a population that actually contribute
succeeding generations. This number is generally lower than the
observed, censused population size, being reduced by the following factors:
1) a higher proportion of one sex may mate; 2) some individuals will pass on
more genes by having more offspring in a
lifetime than others; 3) any severe past reduction in population size may
result in the random loss of one or more particular genes.
- Embryonic diapause
- In some species (e.g. in most kangaroo species), at about the time a female gives birth,
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)
- A species is "endemic" to a particular area if it occurs naturally only in
that area. The term is usually applied to a species with a very limited range, or a species that only occurs in one country.
- A disease that is persistently found in an animal population
- Short-lived, or of brief duration.
- Referring to a plant that lives on the surface of another plant and obtains its moisture
and nutrients from the air and rain.
- A disease outbreak in an animal population that
occurs at a particular time and does not persist (compare "Enzootic").
- A term collectively referring to asses, horses and zebras.
- 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
- A long cliff separating two relatively level or gently sloping surfaces.
- Estrus (adjective: "estrous")
- The period in the estrous cycle of a female mammal when she
is usually attractive to males and receptive to mating.
- Estrous cycle
- In female mammals (other than most primates), the hormonally controlled, regularly
repeated stages by which the body is prepared for reproduction.
- An arm of the sea at the mouth of a river. Usually an estuary is characterized by a two-layer flow, where the top layer consists of fresh water flowing downstream and the bottom layer consists of salt water flowing upstream from the sea.
- The history of a word shown by tracing its development from another
- Referring to an animal that can tolerate a wide range of temperatures ("eury-"
= "broad" or "wide").
- A hard supporting structure on the outside of the body, enclosing all living cells
- Exotic species
- Introduced, non-native species.
- To wipe out.
- A material that has oozed out of something. For example, gum that has oozed out of a tree through a wound in the bark.
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Last modified: December 23, 2005;