Page 491 - (DK) Ocean - The Definitive Visual Guide

GLOSSARY 489

chlorophyll The green pigment of continental shelf The gently sloping current Any sustained horizontal flow dorsal Relating to the back or upper
plants and seaweeds that allows them seabed around the edges of most of water. See also drift, surface current, surface of an animal. See also ventral.
to make their own food by using the continents, formed of continental thermohaline circulation, turbidity drift A broad, slow-moving flow
Sun’s energy. See photosynthesis. crust and averaging around 425 ft current, western boundary current. of surface water; for example,
chromatophore A skin cell in which (130 m) deep. cusp Any shape formed by two the North Atlantic Drift.
the distribution of colored pigment continental slope Sloping seabed at concave lines meeting at a point. drowned coast A coast where the land
can be altered, allowing an animal to the seaward edge of the continental Cusp-shaped ridges of sand are often has sunk or the sea level has risen
change color. Color change may be shelf. It descends relatively steeply created on beaches by wave action. compared with the previous level.
fast, as in cephalopods, or slower, as in to the continental rise. cyanobacteria A group of minute, It may show features such as rias or
crustaceans and some fish. convection Circulating currents in a single-celled organisms, which can fjords. See also emergent coast, fjord, ria.
cilia Tiny beating hairlike structures on fluid—for example air, water, or hot photosynthesize like plants. They are dune A hill or ridge-shaped structure
the surfaces of some cells. Used to aid rock—that result from heated portions classified as bacteria, because they of sand formed by wind action
movement in small organisms, or to rising because they are less dense, have a similar structure. Also called along some coasts and in deserts.
create water currents. Singular cilium. and sinking later as they cool. blue-green algae, although they are Coastal dunes are usually formed
cloaca The combined opening of the copepods Small, swimming not closely related to other algae. on low-lying land behind beaches.
1
digestive, urinary, and reproductive crustaceans, usually less than /16 in See also photosynthesis.
systems of many vertebrates (e.g., fish, (2 mm) long, that make up a large cyclone (1) Also called a depression,
birds) and some invertebrates. part of the zooplankton. There are a pattern of circulating air in the E
also many parasitic and burrowing atmosphere with low pressure at the
cnidarians A major group (phylum)
of invertebrate animals with simple species. See also zooplankton. center. Cyclones normally form over echinoderms A major group (phylum)
bodies bearing tentacles that coral Any of various cnidarians that oceans outside the tropics and are of marine invertebrates that includes
surround a single opening (mouth). live fixed to the ocean bottom, associated with wet and windy starfish, brittle stars, sea urchins, sea
Cnidarians include corals, anemones, secrete skeletons for support, and are weather. (2) See tropical cyclone. lilies, sea cucumbers, and sea daisies.
and jellyfish, and are often colonial. usually colonial. The true corals lay Echinoderms have bodies arranged in
parts rather like the spokes of a wheel
carbonate outside their bodies that D
Their two typical body forms are down hard skeletons of calcium (so-called “radial symmetry”). They
the polyp and the medusa. In some have chalky protective plates under
cnidarians, both forms occur during eventually form coral reefs. Other dark zone Vertical zone of the seabed their skin, and use a unique system
the life cycle. See also colonial, coral, coral groups include the sea fans. See and water column at around 3,300–
medusa, nematocyst, polyp. also cnidarians, sea fans, zooxanthellae. of hydraulic “tube feet” for moving,
13,000 ft (1,000–4,000 m), between
coral bleaching Phenomenon in or for capturing prey, or both.
coast See concordant coast, depositional the twilight zone and abyssal zone.
which coral animals lose their tiny echolocation Method of locating and
coast, discordant coast, drowned coast, Virtually no light penetrates this
symbiotic algae (zooxanthellae), characterizing nearby objects, used
emergent coast, erosional coast, primary deep. See also abyssal, twilight zone.
usually in response to a stress in the by dolphins, bats, and some other
coast, secondary coast. delta An often fan-shaped structure
environment. Bleached corals may animals, by emitting high-pitched
cold seep A natural seepage of oil or of sediment built by the deposition
later die. See also zooxanthellae. sounds and interpreting their echoes.
other energy-containing chemicals of material by a river at its mouth.
coral reef A rocklike, often ridge- echo-sounding The use of sound
on the sea floor, often supporting demersal Of a fish: living mainly near
shaped structure of calcium carbonate equipment to measure the depth
dense concentrations of marine life. the sea floor.
built in shallow tropical seas by of objects or the ocean floor; also
colonial Of an animal: living in generations of coral animals. See deposit feeding Feeding by extracting used as a synonym for echolocation.
colonies. A colony can consist of also barrier reef, fringing reef. food particles from mud or other See also sonar.
separate individuals, as in the case of deposits. See also filter feeding. eddy A circular motion of any size and
sponge shrimp, or animals joined by coralline Resembling coral; mainly depositional coast A coast that is speed in a fluid. Mesoscale eddies of
strands of living tissue, as in the case applied to red seaweeds that form
hard, calcareous crusts on rocks or growing seaward due to deposition of more than 60 miles (100 km) across
of many marine invertebrates, such
in coral reefs. sand and other sediment supplied by are important features of ocean
as corals and bryozoans. Individuals rivers or ocean currents. See also circulation. In tidal currents and
may be specialized for different roles, Coriolis effect Phenomenon resulting emergent coast, erosional coast.
such as feeding, reproduction, and from the rotation of Earth, in detritus Fragments of dead organisms whirlpools, an eddy is a circular
motion slower than a whirlpool.
defense, in which case the colony which winds and currents traveling and organic waste material, often See also gyre, vortex, whirlpool.
may behave like a single animal. See toward or away from the equator mixed with sediment or suspended
also bryozoans, cnidarians, zooid. are deflected to the right in the Ekman effect Tendency for a wind or
Northern Hemisphere and to the in ocean currents. A detritivore is an current to cause air or water above
comb jellies see ctenophores.
left in the Southern Hemisphere. animal that feeds on detritus. or below it to move, but in a
commensal Living in close association The effect helps to explain the diatoms A group of plantlike protists different direction to the original
with an organism of another species, direction of prevailing winds and that are part of the algae and major wind or current. The effect results
for example, by sharing its burrow, the existence of gyres. primary producers in the plankton. from the rotation of Earth. At the
without either helping or damaging They are single-celled but often grow
crabs see crustaceans. ocean surface, the net result is usually
it. See also mutualism, symbiosis. as chains or colonies. Diatoms secrete that a prevailing wind creates a water
crinoids Stalked echinoderms, also
concordant coast Coast on which intricate cases of silica around themselves. current at 90° to the wind direction.
called sea lilies, that filter-feed using
hills and valleys are roughly parallel See also algae, primary producer, protists. See also Coriolis force.
their branching arms. Some species
to the shore, resulting either in a dimorphism see sexual dimorphism.
have no stalks and are known as El Niño Phenomenon by which the
straight coastline or one with rocky
feather stars. See also echinoderms. dinoflagellates A group of protists waters of the eastern Pacific off
islands running parallel to the that bear two flagella. They are South America become warmer than
shoreline. See also discordant coast. crustaceans The most diverse and usual every 4–7 years. The opposite
abundant group of arthropods in common in ocean plankton.
continental crust The material Some are animal-like (eating phenomenon, in which eastern
the oceans. It includes crabs, lobsters,
in Earth’s crust that forms the other organisms), while others are Pacific waters are unusually cold, is
shrimps, barnacles, krill, copepods,
continents, including the continental plantlike (photosynthesizing) and called La Niña. The term El Niño is
isopods, and amphipods. Their jointed
margins. It is lighter and thicker appendages are variously modified are therefore part of the alga. See also used as shorthand for the larger
than oceanic crust. as claws, legs, swimming organs, or also algae, flagellum, protists. phenomenon called the El Niño–
continental margin A continent’s filter-feeding devices, depending discordant coast Coast on which hills Southern Oscillation. See ENSO.
edge below sea level, including the on the species. See also arthropod. and valleys are roughly at right angles emergent coast A coast where the
continental shelf and continental slope. ctenophores Transparent jellyfish-like to the shore, resulting in an indented land has risen or sea level has fallen
continental rise The gently sloping animals that hunt in the plankton. coastline of headlands and bays. See compared with a former level. See
seabed around the edge of ocean They swim using beating hairlike also concordant coast. also drowned coast, isostasy.
basins that adjoins the bottom of the structures arranged in rows called doldrums The region of very light ENSO Used as an abbreviation for
continental slope. comb plates. Also called comb jellies. winds close to the equator. the El Niño–Southern Oscillation.