parasites
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parasites organisms that live inside (endoparasites) or attached to (ectoparasites)
an individual of another species: the host. They have a host-parasite relationship. The parasite consumes body tissue and/or fluids of the host without
killing him. Some species are facultative, other obligate parasites (i.e., incapable of surviving without a host). Parasitic species can have very complicated life cycles and more than one host species may be involved. Kleptoparasites are not parasites in the strict sense, but take the food collected by
other species. ~symbiosis.
parenchyma (1) in plants: tissue of thin-walled cells, not elongated in any direction; (2) in animals: loose tissue consisting of irregularly shaped vacuolated
cells, forming a large part of the body of, e.g., the Platyhelminthes.
parthenogenesis spontaneous development of an egg (without fertilization) into
a new individual; genetically identical to the mother.
partial pressure is the gas pressure exerted by a designated component of a
gaseous mixture.
partial tide the astronomical theory of tides states that tides contain many components of different periodicity: the partial tides, tidal components, or tidal
constituents. In the harmonic analysis of tides these different components are actually analysed from a tidal record. The partial tides are indicated with letters
indicating the astronomical origin of this component (e.g., M = moon, S =
sun) and a number or letter indicating its periodicity (1 = diurnal, 2 = semidiurnal, f = fortnightly, m = monthly, sa = semiannual, a = annual).
particle counter device automatically counting small particles in gaseous or
aqueous media, often with electro-magnetic, electric or optical sensors. An
electric type was originally developed by Coulter Electronics to automatize
blood-cell counting in medical laboratories (Coulter counter); its principle is
based on changes in electrical conductivity induced by particles passing
through a small opening. Particle counters are widely applied in industrial
and aquatic research, e.g., in marine biology to measure the concentration
and the size or volume of particulates in the sea. Modern particle counters
discriminate particles from 0.3 to over 1000 flm in size, at a rate of up to 1000
per second.
particulate organic carbon (POC) all organic carbon contained in particulate organic
matter. Usually separated from dissolved organic carbon (DOC) by filtering over
0.45 flm filters. Contained in living phytoplankton, zooplankton, bacteria as well
as in dead organic particles (detritus). In fact a continuum of organic matter
occurs in the sea from small organic molecules to the largest particles
(whales), the separation of DOC and POC by filtering being artificial and
226
parasites organisms that live inside (endoparasites) or attached to (ectoparasites)
an individual of another species: the host. They have a host-parasite relationship. The parasite consumes body tissue and/or fluids of the host without
killing him. Some species are facultative, other obligate parasites (i.e., incapable of surviving without a host). Parasitic species can have very complicated life cycles and more than one host species may be involved. Kleptoparasites are not parasites in the strict sense, but take the food collected by
other species. ~symbiosis.
parenchyma (1) in plants: tissue of thin-walled cells, not elongated in any direction; (2) in animals: loose tissue consisting of irregularly shaped vacuolated
cells, forming a large part of the body of, e.g., the Platyhelminthes.
parthenogenesis spontaneous development of an egg (without fertilization) into
a new individual; genetically identical to the mother.
partial pressure is the gas pressure exerted by a designated component of a
gaseous mixture.
partial tide the astronomical theory of tides states that tides contain many components of different periodicity: the partial tides, tidal components, or tidal
constituents. In the harmonic analysis of tides these different components are actually analysed from a tidal record. The partial tides are indicated with letters
indicating the astronomical origin of this component (e.g., M = moon, S =
sun) and a number or letter indicating its periodicity (1 = diurnal, 2 = semidiurnal, f = fortnightly, m = monthly, sa = semiannual, a = annual).
particle counter device automatically counting small particles in gaseous or
aqueous media, often with electro-magnetic, electric or optical sensors. An
electric type was originally developed by Coulter Electronics to automatize
blood-cell counting in medical laboratories (Coulter counter); its principle is
based on changes in electrical conductivity induced by particles passing
through a small opening. Particle counters are widely applied in industrial
and aquatic research, e.g., in marine biology to measure the concentration
and the size or volume of particulates in the sea. Modern particle counters
discriminate particles from 0.3 to over 1000 flm in size, at a rate of up to 1000
per second.
particulate organic carbon (POC) all organic carbon contained in particulate organic
matter. Usually separated from dissolved organic carbon (DOC) by filtering over
0.45 flm filters. Contained in living phytoplankton, zooplankton, bacteria as well
as in dead organic particles (detritus). In fact a continuum of organic matter
occurs in the sea from small organic molecules to the largest particles
(whales), the separation of DOC and POC by filtering being artificial and