In biology, a species (plural: species) is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, the difficulty of defining species is known as the species problem. Differing measures are often used, such as similarity of DNA, morphology, or ecological niche. Presence of specific locally adapted traits may further subdivide species into "infraspecific taxa" such as subspecies (and in botany other taxa are used, such as varieties, subvarieties, and formae).
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Some articles on species:
... Most nemertean species have just one pair of nerve cords, many species have additional paired cords, and some species also have a dorsal cord ... In some species the cords lie within the skin, but in most they are deeper, inside the muscle layers ... Some species have paired cerebral organs, sacs whose only openings are to the outside ...
... Comprises 100 marine species ... Comprises about 400 species ... Includes seven species, of which six live as commensals in the mantle of large clams and one in that of a freshwater snail ...
... All species have a proboscis which lies in the rhynchocoel when inactive but everts (turns inside-out) to emerge just above the mouth and capture the animal's prey with venom ... A few species with stubby bodies filter feed and have suckers at the front and back ends, with which they attach to a host ... chemoreceptors, and on their heads some species have a number of pigment-cup ocelli, which can detect light but not form an image ...
... Nearly all non-crop, naturally occurring species observed in comparative farm land practice studies show a preference for organic farming both by abundance and diversity ... An average of 30% more species inhabit organic farms ... Many weed species attract beneficial insects that improve soil qualities and forage on weed pests ...
... Orthopteroid species have a paurometabolous life cycle or incomplete metamorphosis ... The use of sound is generally crucial in courtship, and most species have distinct songs ... The number of moults varies between species growth is also very variable and may take a few weeks to some months depending on food availability and weather ...
More definitions of "species":
- (noun): A specific kind of something.
Example: "A species of molecule"; "a species of villainy"
Famous quotes containing the word species:
“For my own part I think no innocent species of wit or pleasantry should be suppressed: and that a good pun may be admitted among the smaller excellencies of lively conversation.”
—James Boswell (17401795)
“Heaven and hell suppose two distinct species of men, the good and the bad. But the greatest part of mankind float betwixt vice and virtue.”
—David Hume (17111776)
“As kings are begotten and born like other men, it is to be presumed that they are of the human species; and perhaps, had they the same education, they might prove like other men. But, flattered from their cradles, their hearts are corrupted, and their heads are turned, so that they seem to be a species by themselves.... Flattery cannot be too strong for them; drunk with it from their infancy, like old drinkers, they require dreams.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (16941773)