Agnatha
6
can be brought together by turbulence, Brownian movement (only particles
< I-811m), by differences in settling rate or by organisms bringing particles
together in feces, or pseudofeces. Small particles are easily attached to larger ones settling through the water column (scavenging). In the sea large flocs
(0.1-2.0 mm diameter), called marine snow, are ubiquitous, but fragile so that
they are broken during sampling. They can only be studied by in situ observation (diving, underwater photography). -tflocculation.
Agnatha (syn. Cyclostomata, Lampreys, hagfish) class of the Vertebrata. These fish
(-tPisces) are eel-shaped creatures with a naked skin (no scales), and are the
most primitive of all living vertebrates. Instead of the backbone there is an
elastic notochord studded with separate pieces of cartilage. All further parts of
the skeleton are cartilaginous, including the feeble support of the fins. There
are no true jaws, and the gills are found behind one to seven or more separate pores at each side of the body. There are two orders in this class: the
Petromyzoniformes (lampreys) and the Myxiniformes (hagfish). In lampreys the mouth is a circular sucking disk with horny teeth. They live in
freshwater or are anadromous, and are mostly parasitic, sucking blood from
fish and cetaceans (-t mammals, marine). Example: Petromyzon. In hagfish the
mouth has two rows of triangular teeth, the eyes are degenerated, and there
are numerous mucous pores on the body. They are marine scavengers, and
e.g., live from dead fish. Example: Myxine.
air bladder -tgas bladder.
air gun -tseismic instruments.
air-sea exchange (or ocean-atmosphere exchange) the physical and chemical properties of the ocean and the atmosphere are influenced by their mutual
exchange. (1) (phys.) The exchange of heat (including latent heat), water, and
momentum at the sea surface, between the air and the sea strongly influences the physical conditions in both the ocean and the atmosphere. This
exchange is studied by measurement of the transport processes in the
boundary layers and by assessing the budgets of heat, water, and momentum
in these two interacting media. For practical purposes formulas have been
developed that allow for the computation of this exchange from observed
values such as wind, temperature, etc. The turbulence in the boundary layers is
an important factor in the exchange. The exchange of momentum is
expressed by the wind stress. As the exchange of water by evaporation also
involves the latent heat, the heat exchange is also affected. The global differences in the heat and water exchange between ocean and atmosphere are an
important factor in the climate system of the earth. The ocean circulation
that transports heat from the equator to the poles has a considerable effect
on the moderation of the climate; (2) (chem.) the exchange of chemical sub-
6
can be brought together by turbulence, Brownian movement (only particles
< I-811m), by differences in settling rate or by organisms bringing particles
together in feces, or pseudofeces. Small particles are easily attached to larger ones settling through the water column (scavenging). In the sea large flocs
(0.1-2.0 mm diameter), called marine snow, are ubiquitous, but fragile so that
they are broken during sampling. They can only be studied by in situ observation (diving, underwater photography). -tflocculation.
Agnatha (syn. Cyclostomata, Lampreys, hagfish) class of the Vertebrata. These fish
(-tPisces) are eel-shaped creatures with a naked skin (no scales), and are the
most primitive of all living vertebrates. Instead of the backbone there is an
elastic notochord studded with separate pieces of cartilage. All further parts of
the skeleton are cartilaginous, including the feeble support of the fins. There
are no true jaws, and the gills are found behind one to seven or more separate pores at each side of the body. There are two orders in this class: the
Petromyzoniformes (lampreys) and the Myxiniformes (hagfish). In lampreys the mouth is a circular sucking disk with horny teeth. They live in
freshwater or are anadromous, and are mostly parasitic, sucking blood from
fish and cetaceans (-t mammals, marine). Example: Petromyzon. In hagfish the
mouth has two rows of triangular teeth, the eyes are degenerated, and there
are numerous mucous pores on the body. They are marine scavengers, and
e.g., live from dead fish. Example: Myxine.
air bladder -tgas bladder.
air gun -tseismic instruments.
air-sea exchange (or ocean-atmosphere exchange) the physical and chemical properties of the ocean and the atmosphere are influenced by their mutual
exchange. (1) (phys.) The exchange of heat (including latent heat), water, and
momentum at the sea surface, between the air and the sea strongly influences the physical conditions in both the ocean and the atmosphere. This
exchange is studied by measurement of the transport processes in the
boundary layers and by assessing the budgets of heat, water, and momentum
in these two interacting media. For practical purposes formulas have been
developed that allow for the computation of this exchange from observed
values such as wind, temperature, etc. The turbulence in the boundary layers is
an important factor in the exchange. The exchange of momentum is
expressed by the wind stress. As the exchange of water by evaporation also
involves the latent heat, the heat exchange is also affected. The global differences in the heat and water exchange between ocean and atmosphere are an
important factor in the climate system of the earth. The ocean circulation
that transports heat from the equator to the poles has a considerable effect
on the moderation of the climate; (2) (chem.) the exchange of chemical sub-