Zoology glossary ~ I

Zoology Glossary Index:
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Ichthyology
The study of fish.

Ideal Free Distribution
The distribution of individuals across resource patches of different intrinsic quality that equalizes the net rate of gain of each when competition is taken into account.

Imago
The fourth, or adult, stage in the life of certain insects, such as the butterfly or moth.

Immature
"A yong bird no longer under parental care but not yet old enough to breed; a bird that is not yet fully adult." (Source: Sibley)

Imprinting
The tendency of young animals to follow the first moving thing they see. In the wild, this is usually the mother, but in captivity, where the mother may not be the first thing they see, they might follow a human being or any moving object.

Incubation Patch
"A defeathered area on the lower abdomen in which the skin has thickened and become rich with blood vessels." (Source: Sibley)

Inhibition
The suppression of a colonizing population by another that is already established, especially during successional sequences.

Insectivore
Used as a term of classification, this word denotes an insect-eating mammal of the Order Insectovira (such as the shrew). The word is more generally used of any insectivorous creature (such as the bat)‚ a creature that eats mainly insects.

Instinct
Inborn or innate behavior.

Intergrading
"The merging of characteristics of two populations where their ranges come into contact." (Source: Sibley)

Internal Compass
"The hypothesized mechanism that allows organisms to orient themselves so as to proceed in the proper direction during long-distance movements such as migration." (Source: Sibley)

Interstitial Skin
Skin between a snake's scales.

Introduced Species
A species that humans have placed into an ecosystem or community (either accidentally or intentionally) in which it does not naturally occur.

Invasion
"Sudden large movement of individuals into an area where they are generally uncommon, often on an unpredictable basis." (Source: Sibley)

Invertebrate
Animal without a backbone. Invertebrates make up over 90 percent of all animal species.

Irruption
"Sudden large movement of individuals into an area where they are generally uncommon, often on an unpredictable basis." (Source: Sibley)

Isolating Mechanism
An obstacle to interbreeding, either extrinsic, such as a geographical barrier, or intrinsic, such as structural or behavioral incompatibility.