restricted to a single mode of behavior or environmental condition (Morris 1992).

An organism that can sustain life only when thriving in another living organism.

absolute requirement, e.g., obligate aerobe

refers to a response to particular condition or way of life for which there is no alternative; ie. a plant or animal that only lives in a prairie ecosystem.

Essential, necessary; unable to exist in any other state, mode, or relationship; restricted to one particularly characteristic mode of life. An obligate predator lives off of only one species or specific group of prey; an obligate parasite is capable of living naturally only as a parasite and only on its single host; an obligate halophyte is a plant that requires salty soils in order to thrive; an obligate relationship is a relationship between organisms in which neither can exist without the other. [Go to source

(L. obligatus: mandatory) adj. Restricted to particular conditions, circumstances or particular way of life; for example, an obligate parasite is unable to survive without a host. Opposite: facultative.

(3) essential, necessary, unable to exist in any other state, mode or relationship. pen pit mining - (2) a form of mine operation designed to extract minerals that lie near the surface through removal of all overburden resulting in a depression in the earth. (3) a surface mining method in which overlying rock and soil are removed to expose an ore body, which is then drilled, blasted and hauled from the pit.

Refers to an organism that is restricted to a particular set of environmental conditions, without which it cannot survive.

restricted to a particular condition of life; "an obligate anaerobe can survive only in the absence of OXYGen"

Incapable of surviving without a host, as occurs with certain parasites. See also: facultative.

Restricted to one particularly characteristic mode of life or biologically essential for survival.

of parasites, unable to survive without the host. cf. facultative.

restricted to a particular condition of life e.g. dependent on a particular habitat to be able to breed

An adjective referring to an environmental factor (for example, oxygen) which is always required for growth. For example, obligate aerobe. Compare with facultative.

a disease-causing organism that cannot live in the marine environment on its own and must reside in the host tissue to survive.

Necessary; obliged. An obligate parasite is an organism that can live only on living tissue.

Restricted to a particular set of environmental conditions, without which an organism cannot survive. (e.g., an obligate parasite can survive only by parasitizing another organism.) ( 20)