UCMP Glossary: I
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Iapetus Ocean -- n. A relatively small ocean that existed between the continents of Laurentia, Baltica, and Avalonia from the Late Precambrian to the Devonian.
igneous rock -- Any rock solidified from molten or partly molten material.
impressions -- Prints or marks made when an organism’s body has been compressed (flattened). Impressions are different from compressions because no thin organic material is left behind.
ingestion -- The intake of water or food particles by "swallowing" them, taking them into the body cavity or into a vacuole. Contrast with absorption.
ingroup -- In a cladistic analysis, the set of taxa which are hypothesized to be more closely related to each other than any are to the outgroup.
inorganic -- Not containing carbon. Not from living things. Ex., minerals, water, oxygen, etc.
integrin -- adhesive protein of the extracellular matrix in animals.
interbedded -- adj. Describes beds (layers) of rock lying between or alternating with beds of a different kind of rock.
internode -- The region of a stem between two nodes, when there is no branching of the vascular tissue.
intertidal -- The coastal zone measuring from the lowest to the highest tide mark. The intertidal zone is subject to alternating periods of flooding and drying.
intestine -- The portion of the digestive tract between the stomach and anus; it is the region where most of the nutrients and absorbed.
intrusion -- n. Magma (and the rock it forms) that has pushed into pre-existing rock; intrusive- adj.; plutonic- syn. extrusive- ant.
ion -- an atom or small molecule which carries a positive or negative charge.
island arc -- n. A curved chain of islands that rise from the sea floor, usually near a continent. The convex side usually faces the open ocean, while the concave side usually faces the continent, e.g., the Aleutian Islands in Alaska; volcanic arc- syn.
isotope -- One of two or more variations of the same chemical element, differing in the number of neutrons not the number of protons.
