vibraculum
338
vibraculum (pI. vibracula) a modified zooid in Cheilostomata; the operculum of the
zooid is modified into a long bristle, which can be moved in one plane and
is used to sweep away particles settling on the colony. In some free-living
cheilostomes they can also be used in locomotion of the entire colony by
coordinated movements of all the vibracula together.
viroids small pieces of RNA which are not complexed with protein and have viruslike properties.
virtual population analysis an iterative method to estimate fishing mortalities and
stock sizes by year class based on the catch equation and applied to estimate
the age composition of the total landings of a species in consecutive years.
The virtual population in a particular year is defined as the sum of the
catches of each year class constituting the population during subsequent
years, corrected for mortality by natural causes.
virus a genetic element containing either DNA or RNA that is able to alternate
between intracellular and extracellular states, the latter being the infectious
state. Viruses are pathogenic agents, parasitic in bacteria, plants, and animals, unable to multiply outside the host. They are so small « 0.2 11m) that
they pass through filters which retain bacteria.
visceral mass in soft-bodied animals the ventral organs (intestine, stomach,
digestive gland, heart, kidneys) are coalesced into the visceral mass.
viscosity measures the ability of molecular transport to eliminate the nonuniformity of fluid velocity. The molecular transport of momentum in a fluid
depends on the composition of the fluid and its temperature, and is expressed by its viscosity. The dynamic viscosity gives the relation between the
internal friction per unit surface and the current shear; the kinematic viscosity is the dynamic viscosity divided by the density of the fluid.
vitamins are accessory food constituents which are necessary only in minute
amounts for a normal functioning of organisms. Absence or shortage leads
to deficiency diseases. They are part of biologically active substances, e.g.,
vitamin BI2 is primarily released by bacteria and enhances the development
of some phytoplankton species.
Vitiaz Expedition (1886-1889) a Russian round-the-world expedition under s.o.
Makaroff during which in particular valuable physical observations were
made in the North Pacific.
viviparous bringing forth young alive.
338
vibraculum (pI. vibracula) a modified zooid in Cheilostomata; the operculum of the
zooid is modified into a long bristle, which can be moved in one plane and
is used to sweep away particles settling on the colony. In some free-living
cheilostomes they can also be used in locomotion of the entire colony by
coordinated movements of all the vibracula together.
viroids small pieces of RNA which are not complexed with protein and have viruslike properties.
virtual population analysis an iterative method to estimate fishing mortalities and
stock sizes by year class based on the catch equation and applied to estimate
the age composition of the total landings of a species in consecutive years.
The virtual population in a particular year is defined as the sum of the
catches of each year class constituting the population during subsequent
years, corrected for mortality by natural causes.
virus a genetic element containing either DNA or RNA that is able to alternate
between intracellular and extracellular states, the latter being the infectious
state. Viruses are pathogenic agents, parasitic in bacteria, plants, and animals, unable to multiply outside the host. They are so small « 0.2 11m) that
they pass through filters which retain bacteria.
visceral mass in soft-bodied animals the ventral organs (intestine, stomach,
digestive gland, heart, kidneys) are coalesced into the visceral mass.
viscosity measures the ability of molecular transport to eliminate the nonuniformity of fluid velocity. The molecular transport of momentum in a fluid
depends on the composition of the fluid and its temperature, and is expressed by its viscosity. The dynamic viscosity gives the relation between the
internal friction per unit surface and the current shear; the kinematic viscosity is the dynamic viscosity divided by the density of the fluid.
vitamins are accessory food constituents which are necessary only in minute
amounts for a normal functioning of organisms. Absence or shortage leads
to deficiency diseases. They are part of biologically active substances, e.g.,
vitamin BI2 is primarily released by bacteria and enhances the development
of some phytoplankton species.
Vitiaz Expedition (1886-1889) a Russian round-the-world expedition under s.o.
Makaroff during which in particular valuable physical observations were
made in the North Pacific.
viviparous bringing forth young alive.