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Scientific classification : Class (biology)Scientific classification is a means used by biologists to organize each of the organisms on the planet, based primarily on evolutionary similarity as determined by visual observation. This system was devised by Carolus Linnaeus (1707-1778).The system works by placing each organism into a layered hierarchy of groups. Each group at a given layer is composed of a set of groups from the layer directly below. Therefore, in theory, one needs know only the lowest layer (species) of a particular organism in order to uniquely determine the other six layers. In practice, however, many species actually have the same species designation, so when specifiying a species, scientists use the bottom two layers - a system called binomial nomenclature. The standard groupings (taxa) of taxonomy from most general to most specific are: Several acronym mnemonics have been made for these, for instance King Phillip called out for good soup. Sometimes tribes, which lie between families and genera, and races, which lie below species, are also used. Intermediate ranks may be created by adding prefixes, for instance:
The term varieties is sometimes used in place of subspecies. In horticulture, it refers to populations modified by selective breeding, for instance the Peace Rose (http://www.corecom.net/~gardener/Roses/PeaceRose.html), a hybrid Tea Rose. At the top of the scale, there has been a move towards the three domain system. The domains originally were replacements for the different kingdoms, but often count as a higher rank. Could add a description of the difficulty in classifying microbes: their features are derived from direct visual observation, but include such procedural characteristics as Gram stain type, motility, ability to form spores, etc. However, given an unknown bacterium with a given set of characteristics, it is in general not possible to predict its phylogeny, toxicity, etc. Other methods, using genes, their DNA, and several types of RNA, are under development.
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The fruit fly so familiar in genetics laboratories is Drosophila melanogaster. Its usual classification, as well as that of humans, is as follows
| Kingdom | Animalia |
| Phylum | Arthropoda |
| Class | Insecta |
| Order | Diptera |
| Family | Drosophilidae[?] |
| Genus | Drosophila |
| Species | melanogaster |
| Kingdom | Animalia |
| Phylum | Chordata |
| Subphylum | Vertebrata |
| Class | Mammalia |
| Subclass | Eutheria |
| Order | Primates |
| Suborder | Catarrhini[?] |
| Family | Hominidae |
| Genus | Homo |
| Species | sapiens |
| Kingdom | Plantae |
| Division | Magnoliophyta |
| Class | Magnoliopsida |
| Order | Magnoliales |
| Family | Magnoliaceae |
| Genus | Magnolia |
| Species | acuminata[?] |
Note in this last example, that most of the taxa are named after the type genus, Magnolia.
Taxa above the genus level are often given names derived from the type genus. The suffixes used to form these names depend on the kingdom, and sometimes the phylum and class, as follows:
| Taxon | Plants | Algae | Fungi | Animals |
|---|---|---|---|---|
| Division/Phylum | -phyta | -phyta | -mycota | |
| Subdivision/Subphylum | -phytina | -phytina | -mycotina | |
| Class | -opsida | -phyceae | -mycetes | |
| Subclass | -idae | -phycidae | -mycetidae | |
| Order | -ales | -ales | -ales | |
| Suborder | -ineae | -ineae | -ineae | |
| Superfamily | -acea | -acea | -acea | -oidea |
| Family | -aceae | -aceae | -aceae | -idae |
| Subfamily | -oideae | -oideae | -oideae | -inae |
| Tribe | -eae | -eae | -eae | -ini |
| Subtribe | -inae | -inae | -inae | -ina |
See also:
Streams of lava.html">lava.html">lava run down the sides of the mountains during the time of an
and vineyards which are in the neighbourhood.
About 17OO years ago, during the reign of the Roman Emperor Titus, there
Herculaneum, which was situated at about four miles' distance from the
filled up the streets, and quickly covered over the tops of the houses,
buried. The lava which covered it became in time fit for vegetation,
was built over this place where Herculaneum formerly stood. The little
in a poor man's garden at Resina, a hole.html">hole in a well about thirty feet
curiosity to enter into this hole, and, after creeping underground.html">underground for
inhabitants of the village, who had probably never heard of Herculaneum,
pit in the town of Portici, a similar passage underground was discovered,
the earth.html">earth, and clear the passage. They found, at length, the entrance
It was about eighty-eight Neapolitan palms (a palm contains near nine
passages, marked their way with chalk when they came to any turning, lest
directions, and, lying across them, the workmen often found large pieces
These beams and rafters are burned quite black like charcoal, except
rotten wood, and which are like a soft paste, into which you might run
and some are upright. Several magnificent buildings of brick, faced with
cleared away the earth and lava with which they were encrusted. Columns
places; and out of the ruins of the palaces some very fine statues and
see this subterraneous city, and are desirous to carry with them into
place.
** Philosophical Transactions, vol. ix. p. 440.
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