Page 492 - (DK) Ocean - The Definitive Visual Guide

490 GLOSSARY

A worldwide variation in Earth’s fjord A narrow, steep-sided, deep inlet transport of materials by longshore reproduction, or sometimes for
climate pattern and ocean circulation, of the sea, once occupied by a glacier. drift. See also longshore drift. defense. See also cnidarians, polyp.
including the El Niño phenomenon, Fjords have a shallower sill where guyot A flat-topped submarine hydrothermal vent A fissure in a
associated with a change in the they meet the open sea. See also ria. mountain, also called a tablemount. volcanically active region of the
position of warm surface waters flagellum A flexible, microscopic, See also seamount. ocean floor from which superheated,
in the eastern Pacific. hairlike structure used for propulsion gyre A large-scale circulation of surface chemical-laden water emerges. The
erosional coast A coast that is being by some single-celled organisms and ocean currents, typically spanning a energy in the chemicals fuels rich
eroded by the action of the sea. for creating a water current by whole ocean. See also eddy. biological communities via the
Rocky coasts are typically erosional, sponges. It is longer than a cilium. activities of chemosynthetic bacteria
but so are some low-lying, sandy Plural flagella. See also cilia, sponges. and archaea. See also chemosynthesis.
coasts. See also depositional coast. H
flatworms A major group (phylum)
estuary The mouth of a large river. of invertebrates with simple, usually
Used more broadly, the term includes flattened bodies. Free-living forms hadal Relating to the deepest oceanic I
any bay or inlet where sea water are carnivorous; there are also many regions below 20,000 ft (6,000 m),
becomes diluted with fresh water. parasitic species, including tapeworms. within ocean trenches; deeper than ice age Any episode in which Earth’s
eustatic Of sea-level changes: fluke Either of the lobes forming a the abyssal zone. See also abyssal. temperatures were much lower than
today and ice cover more extensive.
occurring worldwide simultaneously, whale’s, dolphin’s, or dugong’s tail. Hadley cell A large-scale circulation The Ice Age (with capitals) refers to a
for example, as a result of melting foraminiferans A group of protists of air in warmer regions, caused by series of such episodes within the last
ice sheets. See also isostasy. whose empty, chalky skeletons are warmed air rising near the equator, 2 million years, the last ending
eutrophication The altering of an a major part of some deep-sea traveling to mid-latitudes, cooling around 10,000 years ago.
aquatic ecosystem by the addition sediments. They are animal-like (they and descending, and returning to iceberg A large fragment of ice calved
of plant nutrients, such as nitrate and feed on other organisms) and include the equator as the trade winds. from the end of a glacier or ice sheet
phosphate. Often caused by humans, both planktonic and bottom-living halocline A boundary between that is in contact with the sea. See
it can greatly change the character of types. See also protists. waters of different salinities, across also calve.
an ecosystem by, for example, causing forced wave A water wave created by which salinity changes rapidly.
algal blooms. See also bloom. See also pycnocline, thermocline. ice cap A mass of permanent ice similar
storm winds at sea. Forced waves are
exoskeleton A skeleton on the outside taller and have a shorter wavelength headland A promontory on a to an ice sheet but smaller in extent.
of an animal’s body, often also acting than swell waves. See also swell wave. shoreline, usually high and rocky and ice lead A channel of open water
as a protective barrier. Arthropods, under strong forces of coastal erosion. among sea ice.
foreshore The part of a shoreline that
such as crustaceans and insects, have See also erosional coast. ice rafting Transport of rocky debris
lies between the average high- and
an exoskeleton. See also arthropods. out to sea, frozen into icebergs. When
low-water marks. See also tides. heat capacity The amount of heat the icebergs melt, the material is
frazil ice Ice in the form of tiny energy that a given substance can deposited as sediment.
F crystals floating on or near the sea absorb for a given rise in temperature. ice sheet A very large mass of
Water has a high heat capacity and
surface. It is the first stage in the
fast ice Sea ice forming a continuous formation of sea ice. See sea ice. so can act as a store of heat. permanent ice covering land, such
as the Antarctic Ice Sheet.
sheet. See also sea ice, pack ice. fringing reef A coral reef just offshore, hermaphrodite An animal that is
both male and female. Animals that ice shelf An extension of an ice sheet
fathom The traditional unit of depth without an intervening lagoon or into the ocean. Ice shelves are
measurement at sea, equivalent to 6 ft stretch of water. See also barrier reef. are both sexes at once are called
simultaneous hermaphrodites. Others anchored to the sea floor at their
(1.83 m). front A vertical or oblique region at start as males then become females, landward end, but farther from the
fault A fracture in Earth’s crust the boundary of two masses of air or or vice versa. Some species change coast, they float on water.
where rocks have moved relative water with different characteristics. sex repeatedly. igneous rock Any rock that originates
to one another either vertically
holdfast A rootlike structure that from the cooling of magma, such as
or horizontally. G anchors a seaweed to rocks but does basalt or granite.
feather stars see crinoids.
not absorb nutrients like a true root. intermediate coast A coast whose
Ferrel cell A large-scale circulation of gabion A wire cage filled with stones. holoplankton Planktonic organisms features are intermediate between a
air in temperate regions, involving air Gabions are used to protect coastlines that spend all of their life as plankton. primary and secondary coast. See also
rising at around 60°N and S, flowing artificially against erosion. See also meroplankton, plankton. primary coast, secondary coast.
southward at a high altitude,
gastropods The group of mollusks holothurians Soft-bodied, sausage- internal wave A wave occurring at the
descending at around 30°N or S, and
that includes snails, slugs, and shaped echinoderms, also called boundary of two different layers of
returning north as the westerlies
pteropods (sea-butterflies). See also sea cucumbers, that feed mainly by the same fluid rather than at the
(westerly winds). See also Hadley cell.
mollusks. swallowing mud and detritus. Their surface—for example, at the boundary
fertilization The union of a male and gill rakers Projections on the insides radial symmetry is not obvious at between two layers of ocean water.
female sex cell (such as a sperm and of the gill supports of some fish that first glance. See also echinoderms. intertropical convergence zone The
an egg cell in animals) as the first step sieve particles entering their mouths. region of air close to the equator
in the production of a new organism hotspot A localized region of where the north and south trade
by sexual reproduction. Some marine glacier An elongated mass of Earth that experiences large-scale winds converge.
animals release eggs and sperm into compressed ice that flows slowly upwelling of magma. As oceanic
downhill. Glaciers that reach the crust moves over a hotspot, a line invertebrate Any animal without a
the sea to meet by chance (external
fertilization), while in others, the male sea give rise to icebergs. of volcanic islands, such as the backbone, ranging from flatworms
transfers sperm directly into the grease ice Stage of formation of Hawaiian islands, may form over to spiders. Of a total of around 30
female’s body (internal fertilization). sea ice in which frazil ice crystals millions of years. major groups (phyla) of animals,
fetch The distance of open ocean congeal to form a soupy texture. hurricane (1) A name for a tropical 29 are composed of invertebrates.
across which a wind is able to blow, See also frazil ice, sea ice. cyclone, especially one occurring irradiance The amount of radiation
and across which waves generated by greenhouse gas A gas, such as water in the Atlantic. See tropical cyclone. falling on a given area.
the wind are traveling. A longer fetch vapor, carbon dioxide, or methane, (2) A wind speed greater than island arc Chain of islands, usually
tends to result in larger swell waves. that prevents heat from radiating 72 mph (116 km/h). including active volcanoes, created by
See also swell wave. from Earth, causing Earth’s surface hydrocarbon Any chemical the collision of the oceanic crust of
filter feeding Feeding by collecting to warm (the greenhouse effect). compound made only of carbon two tectonic plates. One of the plates
and separating food particles from Some greenhouse gas emissions and hydrogen atoms. is subducted beneath the other,
the environment. When the food are natural; others are caused by hydroids Cnidarians that grow as creating a trench on one side of the
particles are suspended in water it human activities. small, branching colonies of polyps arc. See also subduction, ocean trench.
is also called suspension feeding. See groyne An artificial barrier built down attached to rocks or seaweed. Each isopods A group of crustaceans that
also deposit feeding. a beach and into the sea to hinder polyp is specialized either for feeding, usually have flattened bodies. The