Glossary of ALL Terms for Data on EOL


radially symmetric
having equal proportion around a central point or axis
A permanent way having one or more rails which provides a track for cars.
raised beach
A beach or wave cut platform raised above the shore line by a relative fall in the sea level.
raised mire
Rain-fed, potentially deep peatlands occurring principally in lowland areas across much of Northern Europe, as well as in the former USSR, North America and parts of the southern hemisphere.
ramsar site
A wetland protected by the terms of the Ramsar Convention (The Convention on Wetlands of International Importance, especially as Waterfowl Habitat).
range midpoint latitude
The angular distance, north or south of the earth's equator, of the midpoint of the known geographic range of an organism.
A rangeland biome is an anthropogenic terrestrial biome which is primarily used for the rearing and grazing of livestock.
An area of broken, fast flowing water in a stream, where the slope of the bed increases (but without a prominent break of slope which might result in a waterfall), or where a gently dipping bar of harder rock outcrops.
A rare species is a group of organisms that are very uncommon, scarce, or infrequently encountered. This designation may be applied to either a plant or animal taxon, and is distinct from the term endangered or threatened. Designation of a rare species may be made by an official body, such as a national government, state, or province. The term more commonly appears without reference to specific criteria. Rarity rests on a specific species being represented by a small number of organisms worldwide, usually fewer than 10,000. However, a species having a very narrow endemic range or fragmented habitat also influences the concept. Almost 75% of known species can be classified as rare.
A dimensionless ratio unit
record number
An identifier given to the Occurrence at the time it was recorded. Often serves as a link between field notes and an Occurrence record, such as a specimen collector's number
recorded by
A list (concatenated and separated) of names of people, groups, or organizations responsible for recording the original Occurrence. The primary collector or observer, especially one who applies a personal identifier (recordNumber), should be listed first.
a mode of locomotion most often associated with snakes, using unidirectional traveling waves of muscular contraction
A color hue with high wavelength of the long-wave end of the visible spectrum, evoked in the human observer by radiant energy with wavelengths of approximately 630 to 750 nanometers.
[database_cross_reference: Dictionary:]
red clay
Red clay, also known as pelagic clay, accumulates in the deepest and most remote areas of the ocean. Containing less than 30% biogenic material, its composition is a varied mix of very fine quartz and clay minerals, authigenic deposits precipitated directly from seawater, and micrometeorites. Though called "red" because it sometimes takes the color of oxidized iron minerals, it is usually brownish in color. Its ultimate origin is uncertain, but red clay seems to be mostly derived from distant rivers, and windblown dust. Covering 38% of the ocean floor, it accumulates more slowly than any other sediment type, at only 0.1-0.5 cm / 1000 yr.
red list criteria
All new assessments and reassessments on the IUCN Red List use the 2001 IUCN Red List Categories and Criteria. (Version 3.1)
Red Sea
red soil
a larval form of a digenetic trematode that is produced within a sporocyst, has a mouth, pharynx, and gut
A ridge of rocks, lying near the surface of the sea, which may be visible at low tide, but is usually covered by water.
reef edge
reef slope
"fore reef slope": a sand covered, gradual or sharply descending slope; the next-to-deepest part of the fore reef
reef terrace
"fore reef terrace": the uppermost portion of the fore reef; a flat plain beginning at the base of the buttress or mixed zone, at a depth of about 60 m
reflecting superposition eyes
superposition compound eyes where each ommatidium is equipped with a set of plane mirrors, aligned at right angles, forming a square. Rays entering the eye at an oblique angle encounter two surfaces of each mirror box rather than one surface. In this case, the pair of mirrors at right angles acts as a corner reflector. Corner reflectors reflect an incoming ray through 180 degrees, irrespective of the ray’s original direction. This ensures that all parallel rays reach the same focal point and means that the eye as a whole has no single axis, which allows the eye to operate over a wide angle.
refracting superposition eyes
superposition compound eyes where each ommatidium is equipped with a lens cylinder arrangement, producing the equivalent of a pair of lenses, with the first lens producing a small image halfway down the structure and the second lens turning the image back into a parallel beam. In the process the ray direction is reversed. Thus, the emerging beam is on the same side of the axis as the entering beam—the condition for obtaining a superposition image from the whole array.
Regenerators are excavators that dig and continuously maintain burrows in the sediment and by doing so they mechanically transfer sediment from depth to the surface.
Regosols form a taxonomic remnant group containing all soils that could not be accommodated in any of the other RSGs. In practice, Regosols are very weakly developed mineral soils in unconsolidated materials that do not have a mollic or umbric horizon, are not very shallow or very rich in gravels (Leptosols), sandy (Arenosols) or with fluvic materials (Fluvisols). Regosols are extensive in eroding lands, particularly in arid and semi-arid areas and in mountainous terrain.
widely separated
representative record
Up to five of exemplary records per attribute, per taxon, may be labeled as representative records.
The production of new individuals that contain some portion of genetic material inherited from one or more parent organisms
reproduction temperature
reproductive condition
The reproductive condition of the biological individual(s) represented in the Occurrence. Recommended best practice is to use a controlled vocabulary.
reproductive skew
reproductive strategy
timing of reproduction: one reproduction event, (semelparous) or multiple events (iteroparous)
class of tetrapods
An artificial body of water, often contained by a dam, constructed for the purpose of water storage.
plant substance that consists of a complex mixture of organic aromatic compounds such as mono-, sesqui-, and diterpenoids.
respiratory rate
The total amount of oxygen consumed or carbon lost metabolically per unit time
respiratory system
The organs involved in the exchange of carbon dioxide and oxygen including the trachea, bronchi, and lung parenchyma.
resprout ability after clipping
The ability of woody perennials to resprout following top (above ground biomass) removal.
BROT trait database. Traits: units and categories (RespClip), USDA PLANTS database Characteristics Data Fields (Resprout Ability).
resprout ability after disturbance
Resprouting ability after an undefined disturbance that removed most of the aboveground biomass.
BROT trait database. Traits: units and categories (RespDist),
resprout ability after fire
Resprouting ability one year after being ca. 100% scorched or burned by fire.
BROT trait database. Traits: units and categories (RespFire),;
plants able to survive fire by the activation of dormant vegetative buds to produce regrowth
Atlantic Coast Restingas, ecoregion. Vegetation complex ocurring in the seaside lowlands of Brazil, establishing over sea deposits of sandy sediment. It comprises open or scrubby profiles nearer the beaches, while inland it is forms tall forests.
net-like pattern, arrangement, or structure
rhaetian age
International Chronostratigraphic Chart:
rhizomatous plant
a plant having a rhizome, a modified subterranean plant stem that sends out roots and shoots from its nodes
A swollen shoot axis that grows horizontally at or below the substrate surface and produces shoots above and roots or rhizoids below.
[database_cross_reference: POC:curators]
rhizomes or roots
Rhizomes, roots or both (specific bud source is unknown)
The narrow region of soil that is directly influenced by root secretions and associated soil microorganisms.
rhuddanian age
International Chronostratigraphic Chart:
rhyacian period
International Chronostratigraphic Chart:
A submergent coastal landform that forms where sea levels rise relative to the land either as a result of eustatic sea level change; where the global sea levels rise or isostatic sea level change; where the land sinks. When this happens valleys which were previously at sea level become submerged.
rice field
A paddy field for the cultivation of rice.
A long and narrow upland with steep sides.
A shallow stretch of a river or stream, where the current is above the average stream velocity and where the water forms small rippled waves as a result. It often consists of a rocky bed of gravels or other small stones.
rift lake
A lake which forms as a result of subsidence along a geological fault in the Earth's tectonic plates.
A narrow and shallow incision into soil resulting from erosion by overland flow that has been focused into a thin thread by soil surface roughness. Rilling, the process of rill formation, is common on agricultural land and unvegetated ground.
An incised meander on a river.
riparian wetland
Natural freshwater surface streams of considerable volume and a permanent or seasonal flow, moving in a definite channel toward a sea, lake, or another river; any large streams, or ones larger than brooks or creeks, such as the trunk stream and larger branches of a drainage system.
river bank
The sloping margin of a river, serving to confine it to its natural channel.
river bed
The channel bottom of a river; the physical confine of the normal water flow.
river island
An island that lies in a river.
river mouth
The end of a stream where it enters a standing water body such as a lake, sea or ocean.
river valley
A valley that contains, and has been formed by, a river.
rna:dna ratio
ratio of RNA to DNA biomass fractions in an organism
roadian age
International Chronostratigraphic Chart:
roadside soil
A mass of the mineral material of the crust of the Earth.
An irregular mass of fallen rock at the base of a cliff or steep slope.
A shallow cave-like opening at the base of a bluff or cliff.
rocky desert
rocky grassland
rocky outcrops with vegetation
Inselbergs or rock outcrops surrounded by vegetation
rocky sand
root crown
A root crown, also known as the root collar or root neck, is that part of a root system from which a stem arises.
root feeder
herbivorous animal which eats primarily roots
root nodule
Root nodules occur on the roots of plants that associate with symbiotic nitrogen-fixing bacteria.
rooting depth
It is calculated from the deepest soil layer where roots were present and the longest root measured in the layer.
[database_cross_reference: GR:pj] [database_cross_reference: PMID:12582650]
root: A plant axis (PO:0025004) that is part of a root system (PO:0025025).
[database_cross_reference: POC:curators]
a circular arrangement of leaves or of structures resembling leaves. In flowering plants, rosettes usually sit near the soil. Their structure is an example of a modified stem in which the internode gaps between the leaves do not expand, so that all the leaves remain clustered tightly together and at a similar height
rubber plantation
Ruderal or weedy species are the first to colonize disturbed areas. They are fast-growing and rapidly complete their life cycles, and generally produce large numbers of offspring.
The act of locomoting on limbs with body off the ground such that periodically none of the limbs are touching the ground.
rupelian age
International Chronostratigraphic Chart: