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humic acids
rise above that of the surrounding water, but, as the body temperature does
not remain constant, they are strictly speaking not homeotherms. Compare
poikilotherm.
homing an oriented movement of an animal towards a specific site used for
breeding, resting, hibernating, etc. Feeding excursions of invertebrates such
as limpets (Patella), periwinkles (Littorina), and fiddler crabs (Uca), often
end at the starting point. The mechanism of orientation is not always clear.
There are several alternative hypothetical cues such as orientation to gravity, the magnetic (earth) field, celestial cues, the sun, or a form of orientation
based on smell (olfaction) or memory of past movements (kinesthetic memory), while in intertidal snails retracing of mucous trails has been observed.
homoiotherms ~homeotherms.
Hoplocarida (mantis shrimps) superorder of the class Malacostraca, subphylum
Crustacea (phylum Arthropoda). Predators of fish, crabs, shrimps and Mollusca.
The second pair of thoracic appendages is enormously developed into
smashing or spearing claws for raptorial feeding. Mostly tropical, but also in
the north Atlantic (e.g., Squilla). Living in burrows in the seabed, which they
leave when feeding.
horizon, (reflecting) major layer of seismic reflection of the ocean floor. Three
horizons are distinguished: horizon A is the uppermost reflecting horizon;
horizon B is the lowermost reflecting horizon and horizon ~ is a horizon
occurring between horizons A and B. ~reflection shooting (seismic).
host-parasite relationship ~parasites.
hot spot a localized region on the earth's surface where the geothermal heat flow is
unusually high. Hot spots spring from the mantle and are often inferred from
volcanic activity in the lithosphere above. When lithosphere drifts over the
spot (~plate tectonics) a succession of locations are uplifted by heating. This
process produces a chain of islands (island chain), commonly bearing active
or extinct volcanoes on top. A prominent example is the Hawaii-Emperor
chain, where volcanism at Hawaii marks the present-day location of the hot
spot.
hot spring ~hydrothermal vent.
HPC hydraulic piston corer, ~corer.
humic acids marine humic acids and humic substances are polymerized compounds, containing parts of amino acids, sugars and fatty acids with surface-
humic acids
rise above that of the surrounding water, but, as the body temperature does
not remain constant, they are strictly speaking not homeotherms. Compare
poikilotherm.
homing an oriented movement of an animal towards a specific site used for
breeding, resting, hibernating, etc. Feeding excursions of invertebrates such
as limpets (Patella), periwinkles (Littorina), and fiddler crabs (Uca), often
end at the starting point. The mechanism of orientation is not always clear.
There are several alternative hypothetical cues such as orientation to gravity, the magnetic (earth) field, celestial cues, the sun, or a form of orientation
based on smell (olfaction) or memory of past movements (kinesthetic memory), while in intertidal snails retracing of mucous trails has been observed.
homoiotherms ~homeotherms.
Hoplocarida (mantis shrimps) superorder of the class Malacostraca, subphylum
Crustacea (phylum Arthropoda). Predators of fish, crabs, shrimps and Mollusca.
The second pair of thoracic appendages is enormously developed into
smashing or spearing claws for raptorial feeding. Mostly tropical, but also in
the north Atlantic (e.g., Squilla). Living in burrows in the seabed, which they
leave when feeding.
horizon, (reflecting) major layer of seismic reflection of the ocean floor. Three
horizons are distinguished: horizon A is the uppermost reflecting horizon;
horizon B is the lowermost reflecting horizon and horizon ~ is a horizon
occurring between horizons A and B. ~reflection shooting (seismic).
host-parasite relationship ~parasites.
hot spot a localized region on the earth's surface where the geothermal heat flow is
unusually high. Hot spots spring from the mantle and are often inferred from
volcanic activity in the lithosphere above. When lithosphere drifts over the
spot (~plate tectonics) a succession of locations are uplifted by heating. This
process produces a chain of islands (island chain), commonly bearing active
or extinct volcanoes on top. A prominent example is the Hawaii-Emperor
chain, where volcanism at Hawaii marks the present-day location of the hot
spot.
hot spring ~hydrothermal vent.
HPC hydraulic piston corer, ~corer.
humic acids marine humic acids and humic substances are polymerized compounds, containing parts of amino acids, sugars and fatty acids with surface-