Page 495 - (DK) Ocean - The Definitive Visual Guide

GLOSSARY 493

mainland or another island. See spit. V
spreading ridge see mid-ocean ridge. suspension feeding see filter feeding. tombolo A spit linking an island to the
spring tide The highest high tide swash The movement of turbulent
and lowest low tide within an water up a shore after a wave breaks. trade winds Prevailing winds blowing ventral Relating to the lower surface
approximately two-week cycle, The swash zone is the zone of a shore from the east toward the equator in or belly of an animal. See also dorsal.
caused by the Sun and the Moon where swash typically occurs. subtropical and tropical latitudes.
vertical migration Behavior of many
being in positions in which their swell waves Regular, smoothly transform fault A fault in which the zooplankton, fish, and squid of the
gravitational effects add together traveling waves on the open ocean, rocks on either side are displaced open ocean, in which they rise nearer
most strongly. See also tides, neap tide. especially when at a distance from horizontally. Numerous transform the surface by night and sink deeper
squid see cephalopod. the winds or storms that originally faults occur at right angles to mid- by day, probably to escape predators.
stack see sea stack. caused them. See also fetch. ocean ridges. See also plate tectonics. vertical transport Any large-scale
standing wave A wave that stays swim bladder A gas-filled organ in trench see ocean trench. vertical flow of ocean water.
in the same position rather than many fish, used to control buoyancy, tropical Relating to the warm regions vortex A fast-rotating eddy in a fluid;
moving along, found in particular and sometimes for other purposes of Earth that lie between the equator sometimes used as a synonym for
situations such as tidal races. such as sound production. and the tropics of Cancer and whirlpool. See also eddy, whirlpool.
starfish A group of echinoderms, also symbiosis A close living relationship Capricorn, at latitudes of 23.5° north
called sea stars, having five or more between two species, especially one and south, respectively. The term is
“arms” (extensions to the body) in which both benefit. See also sometimes used loosely for W
and both mouth and anus on the mutualism, commensalism. phenomena typical of these regions,
underside. They swallow their prey even when occurring north or water column The volume of water
whole, which can be very large for south of the two tropics. between the ocean surface and the
their size. See also echinoderms. T tropical cyclone A large-scale, bottom of the ocean.
storm beach The topmost ridge of circulating weather system in warmer wave A motion or disturbance that
tablemount see guyot.
sediment on a beach, usually formed latitudes, called by different names, transfers energy. The water in a wave
tabular Of an iceberg: very wide and crossing the open ocean does not
by the highest spring tides in such as hurricane and typhoon,
combination with storm conditions. flat-topped. in different parts of the world. It move significantly except up and
See also berm, spring tide. tectonic plate Any of the large rigid generates intense winds and torrential down as the wave passes. The high
storm surge A rapid rise in sea level sections into which Earth’s crust and rain. Its energy comes from the water point of a wave is its crest and the
low point its trough. Water motion
caused by storm winds driving water uppermost mantle are divided, whose vapor rising from warm seas and then becomes more complex and turbulent
toward a shoreline. It can cause relative movement is the subject of condensing. A less powerful version in waves breaking on shores
disastrous coastal flooding, especially plate tectonics. The African Plate and of the phenomenon is called a (breakers).
if occurring at the same time as a the Pacific Plate are examples. See tropical storm. See also cyclone,
high spring tide. plate tectonics. hurricane, latent heat, typhoon. westerlies Prevailing winds that blow
terrigenous Of marine sediments: tsunami A sometimes huge water wave from the west. Westerlies are the most
subantarctic Relating to latitudes
originating on the land (for example, usually generated by displacement of common winds in temperate regions.
immediately north of the
carried to the sea by rivers). water by an earthquake and capable western boundary current A relatively
Antarctic Circle.
subarctic Relating to latitudes thermocline A region at a particular of devastating shorelines thousands of narrow, fast-moving surface current
formed at the western boundary of an
miles from its origin. Sometimes
immediately south of the depth in the ocean or height in the inaccurately called a “tidal wave.” ocean basin, usually as part of a gyre.
Arctic Circle. air where average temperature
changes rapidly. See also pycnocline. tube worms Worms that live anchored The Gulf Stream is an example.
subduction The forcing down of and protected in tubes, which are Deep-water western boundary
oceanic crust belonging to one thermohaline circulation The part either secreted or built of material currents also exist. See also gyre.
tectonic plate beneath another of the ocean’s water circulation such as sand grains. Tube worms whirlpool A powerful eddy or vortex
plate when two plates are colliding. powered by differences in the salinity include the giant worms living formed at the sea’s surface, often
Ocean trenches are the location and temperature of different water around some hydrothermal vents, caused when two separate tidal
of such subduction zones. masses, rather than by the wind.
Thermohaline circulation is the cause as well as many segmented worms. currents meet. See also eddy, vortex.
sublittoral Relating to the coastal
of most deep-water and some surface See also polychaetes. white smoker A deep-ocean
marine environment below the
currents. See also surface current. tunicates A group of mainly filter- hydrothermal vent in which the
low-water mark.
tidal bore A single large wave created feeding marine invertebrates closely emerging hot water appears white
submersible A vessel built to operate related to backboned animals because of light-colored mineral
when an incoming tide moves up a
underwater. Some submersibles are (vertebrates). There are both solitary particles suspended in it.
narrowing channel, such as an estuary.
designed to be able to withstand and colonial species. They include worm Any of a variety of usually non-
great pressures in order to explore tidal bulge or trough see tides. non-moving attached forms (sea- swimming invertebrate animals that
the ocean depths. tidal current see tides. squirts) and others that drift in the are long, slender and flexible, and lack
sunlit zone The topmost layer of ocean tidal flat A flat, muddy area covered plankton. See also salps. legs and shells. See flatworms, ribbon
water, where enough light penetrates at high tide; characteristic of sheltered turbidity current A phenomenon worms, segmented worms, tube worms.
for photosynthesis to occur. Also areas such as estuaries. similar to an underwater avalanche or
called the photic zone, it extends from tidal race A strong current created landslide, involving water laden with
the surface to up to 660 ft (200 m). when a tide-generated water flow sediments slipping down a slope. Z
See also dark zone, twilight zone. moves through a narrow channel.
twilight zone The vertical zone of
surf zone The zone on a shore where tide rip A stretch of turbulent water the water column and seabed lying zoea The planktonic larval stage of
waves break and create foaming, where different tidal currents meet. between approximately 660 and certain crustaceans, including crabs.
turbulent water. They are different in structure from
tides Fluctuation in sea level resulting 3,300 ft (200 and 1,000 m) deep, into
surface current Any current flowing from the gravitational attraction of which some light penetrates, but not their adult forms, having long spines.
at the surface of the ocean—for the Sun and the Moon on Earth’s enough to support photosynthesis. zooid An individual in a colony of
example, the Gulf Stream. Surface oceans, combined with Earth’s own typhoon see tropical cyclone. interconnected animals, such as
currents are mainly caused by friction rotation. In the open oceans, each bryozoans. The term is not applied
from prevailing winds. See also tidal cycle of just over 12 hours to colonial coral animals, which are
current, thermohaline circulation. generates a small but measurable U termed polyps. See also polyp.
surface tension The attraction vertical rise (tidal bulge) and fall zooplankton Any animals or animal-
between water molecules at a water (tidal trough) in the water. Tidal effects upwelling The upward motion like protists that are part of the
surface, which creates a thin film with are much more obvious near the of deep-ocean water toward the plankton. See also plankton.
the strength to resist small deflections, coast, and lead to horizontal water surface. Some upwelling increases zooxanthellae Symbiotic, microscopic
allowing some insects, for example, to movements (tidal currents) as well ocean fertility by recirculating algae living in the tissues of many
walk on the water surface. as vertical movements. nutrients from deeper layers. corals. See also symbiosis.