A massive coral growth on a submerged mountain range or volcano, common in the Indian and Pacific Oceans. The only English word derived from the Maldivian language, an atoll is a large coral reef, containing low inhabitable islands, encircling a sea water lagoon.
A region of DNA that is absent on the chromosome of an organism but absent from closely related organisms (i.e., the opposite of a genetic island). The loss of such genetic material may confer a distinctive phenotype. For example, absence of certain genes from E. coli enhances virulence.
circular, or near circular coral reef appearing as a low coral island or a ring of closely spaced coral islets encircling a shallow lagoon in which there is no pre-existing land, and surrounded by deep water of the open sea, formed above an underwater volcano. arometric pressure: a measure of the force exerted by the atmosphere used to forecast the weather.