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Kinds of
Ecosystems
Chapter 4
“In all things of nature there is something of the marvelous.”
Aristotle, Greek Philosopher
Biomes of the World
• Earth is covered by hundreds of types of ecosystems
which are grouped into a few biomes
• Biomes have distinctive climates, plants and organisms;
they are named for their plant life but the main
determinant is the climate (temperature, precipitation,
humidity, winds)
• Most organisms are adapted to live within a particular
range of temperatures and will not survive at
temperatures too far above or below their range.
• There are nine terrestrial biomes in the world: tropical
rain forest, temperate forest, taiga, savanna, grasslands,
chaparral, desert, tundra, mountains
Latitude and Altitude
• Biomes, climate and vegetation vary with latitude
and altitude.
• Latitude is the distance north or south of the
equator and is measured in degrees.
• Altitude is the height of an object above sea level.
• Climate gets colder as latitude and altitude
increase. Therefore, climate also gets colder as
you move farther up a mountain.
Biomes and Vegetation
• Biomes are described by their vegetation
because plants that grow in an area determine
the other organisms that can live there.
• Plants in a particular biome have characteristics,
specialized structures, or adaptations that allow
the plants to survive in that biome (size, shape,
color) ex: plants in tunda tend to be short, cactus
in deserts have no leaves
Forests:
Tropical Rainforests
• Occur in a belt around the Earth near the equator
• Always humid and warm; get about 250 cm (100 in) of rain per
year
• Get strong sunlight year-round; maintains a climate with little
seasonal variation in temperature.
• Ideal climate for growing plants; nourishes more plant species
than any other biome (1 hectare temperate forest contains 10
species of trees/ same area of tropical rainforest contain over
100 species)
• Soil is not rich, usually thin and poor; rapid decay of plants and
animals return nutrients to soil---used up by plants or washed
away by rainfall
• Trees form aboveground roots—growing sideways from the
trees, providing extra support
Rainforest: Plant Adaptations
• Plants grow in layers; trees more than 30 m (100 ft) tall
form a dense canopy-absorbs at least 95% of the
sunlight
• Little light reaches below the canopy (understory); only
trees and shrubs adapted to shade can grow (ex: herbs
with large flat leaves)
• When trees fall, tree seedlings adapted to grow quickly
outcompete other seedlings
• Orchids and monkey ladder vines use the tall tree trunks
for support high in the canopy
Layers of the Rain Forest
• There are four main layers above the forest
floor: the emergent layer, the upper canopy,
the lower canopy, and the understory
• The top layer, the emergent layer, consists of
the tallest trees (60-70 m); trunks can measure
up to 5 m around; they grow and emerge into
direct sunlight; animals such as eagles, bats,
monkeys, and snakes live in the emergent
layer
Layers of the Rain Forest…con’t
• The next layer, the canopy, is the primary layer of
the rain forest; trees grow more than 30 m tall; they
form a dense layer that absorbs up to 95% of the
sunlight; divided into two (upper and lower canopy);
the lower canopy receives less light than the upper
canopy; epiphytes grow in upper canopy and use
the entire surface of a tree as a place to live;
capture lots of sunlight, water and nutrients from
the rain; most animals live in the canopy to feed on
the flowers and fruits that grow there
Layers of the Rain Forest…con’t
• The bottom layer, the understory, receives very little
light; trees and shrubs are adapted grow in low light
conditions; they grow to about 3.5 m tall; herbs with
large, flat leaves grow on the forest floor must be
able to grow in darker spots and get only the small
amount of sunlight that reaches there; when trees
fall, seedlings from trees must grow quickly to
compete with other seedlings
Rainforest: Animal Adaptations
• Incredible diversity of vegetation may have led to the evolution
of the greatest diversity of animals anywhere on Earth
• Little competition; most animals are specialists and are adapted
for a specific purpose
ex: antwrens – variety of species that eat insects at
different layers; flowering plants that can be pollinated by only
one species of insect, bat or bird
• Some animals have developed elaborate methods for escaping
predators; others have equally evolved methods of capturing
their prey
ex: insects (butterfly) that looks like a leaf or twig; frogs
that blend perfectly with plants; poisons on their skin with
bright colors to warn predators
Threats to Rainforests
• Used to cover 20% of Earth’s surface; today, only about
7%
• Every year tropical rainforests are stripped by logging
operations or cleared for farming or cattle grazing (the size
of North and South Carolina combined)
• As they disappear, so do the habitats, plants and animals
become extinct
• Traditions and cultures are lost as native people are
displaced
• Help save the rainforests by looking for rain-forest friendly
products and support organizations that preserve tropical
forests
Temperate Rain Forest
• Found in North and South America, Australia and New
Zealand
• Pacific Northwest is home of the only North American
temperate rainforest
• 300 ft tall evergreen trees (Sitka spruce, Douglas fir)
dominate the forest; mosses, lichens and ferns are
abundant
• Moisture pervades everything; cool, humid forest
• Located at 48° north latitude; rarely freezes (Pacific Ocean
moderates the temperature)
4.3: Temperate Deciduous Forests
• Occur between 30° and 50° north latitude; seasonal
variations can be extreme and growing season is from 4 to
6 months
• Trees drop their leaves in the fall; summer temperatures
can soar to 35° C ( 95° F); winter temperatures plummet
below freezing
• Deciduous forests are moist receiving 75-250 cm (30-100
in) of precipitation
• Rain and snow help decompose dead organic matter
(leaves) contributing to the deep, rich soil
Deciduous Forests: Plant Adaptations
• Plants grow in layers; forest canopy is dominated by tall
trees (maple, oak, birch)
• Small trees, shrubs, bushes grow in the understory
• Forest floor gets more light than the rain forest floor, thus
more ferns, herbs and mosses grow there
• Plants are adapted to survive seasonal changes; seeds,
bulbs and rhizomes become dormant in the ground, trees
lose their leaves
• In spring, as sunlight increases and temperatures
increase, leaves re-emerge on trees, seeds germinate and
rhizomes and roots put forth new shoots
Deciduous Forests: Animal Adaptations
• Animals are adapted to forage the forest plants for food and
shelter
• Squirrels eat nuts, seeds and fruits; bears eat leaves and
berries, deer eat leaves from trees and shrubs; birds nest in
the tops of trees
• Birds are migratory—fly south in the winter to avoid the
harsh weather; return in spring
• Animals that stay use various strategies for survival—bears
and squirrels become inactive; insects enter a state of very
low metabolic activity
Taiga
• Aka: boreal forest; has rough terrain and the forest floor is
sparsely vegetated
• Trees seem barren until you look up to see the green tops
• Located across the northern hemisphere just below the
Arctic Circle; winters are 6 to 10 months and extremely cold
with subfreezing temperatures that plummet to -20°C (-4°F).
• The frost-free growing season may be as short as 50 days
depending on the latitude; enhanced only by constant
daylight during the summer months
Taiga: Plant Adaptations
• Trees whose seeds develop cones (conifers, such as, pine,
hemlock, fir, spruce) do not shed their needle-shaped leaves;
narrow shape leaves and waxy coating retain water when
moisture in the ground in frozen
• The shape (pointed) of the tree helps it shed snow; otherwise
the snow would crush the tree
• Conifer needles (contain acidic substances), acidify the soil
when they fall, preventing other plants from growing;
blueberries, a few ferns and mosses can survive the acidic
soil
• Climate and acidity hinder decomposition which results in
slow soil formation
Taiga: Animal Adaptations
• This biome is dotted with lakes and swamps in the
summer, attracting birds that feed on insects, fish
or other wetland organisms
• Birds migrate south in the winter; shrews and
voles burrow underground; moose and arctic hare
eat whatever vegetation they can find; lynx, wolves
and foxes eat the hare and shed their brown
summer fur and re-grow a thick white fur in the
winter
4.4: Grasslands, Chaparral, Deserts and Tundra
• Climates with less rainfall:
forests  savannas, grasslands, chaparrals  deserts
• As precipitation decreases, so does the diversity of species
present
• Number of different species is smaller, individuals of each
species is even smaller
• Another type of “desert” is present far to the north. It is
called the tundra. Very little precipitation occurs here and
temperatures stay very cold year round
Savannas
• Parts of Africa, western India, northern Australia and
some parts of South America are covered by
grasslands called savanna; located in tropical and
subtropical areas, between tropical rain forests and
deserts
• West African plains contain the greatest collection of
grazing animals on Earth and the predators that hunt
them
• Not many trees, too little rainfall
• Savannas have a wet season and a dry season;
grass fires may sweep across savannas in the dry
season
Savannas: Animal Adaptations
• Migratory lifestyle of the large, grazing herbivores,
such as the elephant
• Animals follow the rains to newly sprouted grasses
• Predatory animals follow their mobile food source
• Give birth during rainy season when food is more
abundant and survival is greatest
• Avoid competition by eating vegetation at different
heights; ex: small gazelle grass on grasses, black
rhinos browse on shrubs and giraffes feed on tree
leaves
Savannas: Plant Adaptations
• Most rain falls during the wet season, therefore,
plants must be able to survive long periods without
water
• Savanna trees and grasses have horizontal
underground root systems to obtain water and
enable them that survive long dry seasons and
regrow quickly after fires
• Course savanna grasses have vertical leaves
• Trees and shrubs have thorns or razor sharp leaves
– deter herbivores
Temperate Grasslands: Prairies, Steppes and
Pampas
• This biome is dominated by grasses and has very
few trees; hot summers and cold winters;
temperate grassland can receive 50 to 88 cm of
precipitation per year
• Grasslands have the most fertile soil of any biome
• Many natural temperate grasslands have been
replaced with crops of corn, soybean and wheat
• Grasslands at one time covered 42% of the total
land surface on Earth; today, they cover only
about 12%
Temperate Grasslands: Prairies, Steppes and
Pampas
• Found on interiors of continents where there is too
little rainfall for trees to grow; prairies of North
America, steppes of Russia and Ukraine, pampas
of South America
• Mountains play a crucial role in maintaining
grasslands by blocking rain clouds thus maintaining
low rainfalls; rainfall increases as you move
eastward, thus larger grasses/shrubs can grow
• Sizzling summer temperatures make grasslands a
tinderbox; fire is common in grasslands
Temperate Grasslands: Plant Adaptations
• Prairie grasses are perennials, surviving from year
to year
• Root systems form dense mats the survive drought
and fire and hold the soil in place
• Rainfall determines what type of grasses will grow
in an area
• Few trees will survive on the grasslands because
of drought, fire and constant battering of winds
Temperate Grasslands: Animal Adaptations
• Grazing animals (pronghorn antelope and
American Buffalo) have large, flat back teeth for
chewing coarse prairie grasses
• Grazers cope with severe winters by growing thick
coats of fur which they shed in spring
• Badgers, prairie dogs, owls live in protected
underground burrows; these burrows shield them
from fire, the elements and predators
Threats to Temperate Grasslands
• Cultivation and overgrazing have changed the
grasslands
• Grain crops have replaced native grasses and
cannot hold the soil in place as well because their
roots are shallow, resulting in soil erosion
• Overgrazed animals are constantly chewing down
the grasses hindering them from regenerating or
holding the soil, thus furthering soil erosion;
constant use is changing the fruitful grasslands into
less productive, desert like biomes
Chaparral
• A type of temperate woodland biome; have fairly
dry climates but get enough rainfall to support
more plants than a desert; have scattered trees
communities (coniferous trees such as pinon
pines, junipers)
• Occurs in the mid-latitudes (30 degrees north and
south of the equator)
• Lies primarily in coastal areas that have
Mediterranean climates, ex: Hollywood, Calif
• Known for their hot, dry summers; mild, wet
winters; and slight variations in seasonal
temperatures
Chaparral: Plant Adaptations
• Mostly low-lying evergreen shrubs and small
trees
ex: chamise, manzanita, shrub oak, olive
trees and cooking herbs like sage and bay
• Plants have small, leathery leaves that resist
water loss; they contain oils that promote burning
• Natural fires destroy trees that compete with
chaparral plants, thus allowing light and space for
the smaller plants
• Plants are well adapted and can regrow from
small bits of surviving tissue
Chaparral: Animal Adaptations
• Common adaptation is camouflage – shape or
coloring that allows them to blend with their
environment
• Quail, lizards, chipmunks and mule deer have
brownish gray coats that allows them to move
through the brush
• Animals have adapted to seasonal differences for
food
ex: scrub jay (bird) has a beak adapted for a
varied diet (insects, seeds, other birds’ eggs
and baby birds)
Threats to the Chaparral
• Biggest threat worldwide is human
development
• This biome has lots of sun, access to
oceans and mild year-round climates which
is inviting to humans
4.5 Deserts
• They are the driest places on Earth,
receiving less than 25 cm (10 in) of
precipitation a year
• Hot deserts occur closer to the equator than
cold deserts
• Often occur in the rain shadow of
mountains (leeward side of the mountain)
Deserts: Plant Adaptations
• Plants in the desert have adaptations for obtaining and
conserving water
• Succulents and cacti have thick, fleshy stems and leaves
that store water; have waxy coating to prevent water loss
• Spines deter thirsty animals from eating plant’s juicy flesh
• Roots are shallow and spread out widely
• Plants are adapted to drought, will die when it is too dry,
drop their seeds which lie dormant until the next rainfall
when they germinate, grow and bloom before the soil
becomes dry again (drought-resistance) ); adapted to
survive even when their water content falls below 30% of
their mass (water levels between 50% to 75% are fatal for
most plants)
Deserts: Animal Adaptations
• Reptiles (gila monsters, rattlesnakes) have thick,
scaly skins that prevent water loss
• Amphibians (spadefoot toad) survive scorching
desert summers by burying themselves in the
ground and sleeping through the dry season
(estivating)
• Insects and spiders are covered with body armor to
help them retain water
• Most animals are activate at night or at dusk, when
the air is cooler
Threats to the Desert
• In the American West, residential development
encroaches upon the desert areas
• Off-road and all-terrain vehicles kill desert
vegetation, destroying habitats of endangered
animals (desert tortoise)
• Humans removing desert plants endanger plant
populations
Tundra
• Lies north of the Arctic Circle; has no tall trees
• Frozen soil supports mostly tough grasses and
shrubs
• Summers are short; only a few inches of the soil
thaws; becomes dotted with bogs and swamps
during the thaw periods; makes an ideal breeding
ground for huge numbers of swarming insects
(mosquitoes, blackflies) and birds that feed on
them
• Under soil lies the permafrost (permanently frozen
soil)
Tundra: Plant Adaptations
• Mosses and lichens cover acres of rocks (don’t
need soil to grow)
• Where soil (thin) exists, plants have shallow, wide
roots which anchor them against arctic winds
• Flowering plants (moss campion, gentian) are tiny
and hug the ground for warmth and to stay out of
the wind
• Woody plants and perennials (willow, junipers)
have evolved dwarf forms and grow flat or trailing
• Plants grow and flower quickly (short summers)
Tundra: Animal Adaptations
• Millions of migratory birds breed during the short
summer because of the abundant food supply
(plants, mollusks, worms, insects)
• Caribou and reindeer migrate; wolves prey on the
caribou, deer, moose, lemmings, mice and rabbits.
• Rodents burrow underground during winter
• Year-round residents (arctic fox) have white fur in
winter; coats are extremely well insulated (musk
ox)
Threats to the Tundra
• One of the most fragile biomes on Earth
• Food chains are relatively simple and can be
disrupted easily
• Conditions are so extreme, land is easily
damaged and slow to recover.
• Oil extraction and transport across land has
brought humans to the area, which has disturbed
the delicate balance of the biome
4.6 Freshwater Ecosystems
• The types of organisms in an aquatic ecosystem
are mainly determined by the water’s salinity; The
amount of dissolved salts the water contains
• Divided into two aquatic groups depending on the
salinity: freshwater ecosystems and marine
ecosystems
• Freshwater ecosystems include sluggish waters
of lakes and ponds, moving waters of rivers and
streams and areas where land and water come
together
Lakes and Ponds
• Littoral zone – where aquatic life close to shore is diverse
and abundant; nutrient-rich area
• Further out, where there is still sunlight for photosynthesis,
live the phytoplankton (plants) and zooplankton (tiny
animals)
• Deep lakes and ponds (too little light) contain a few fish
adapted to cooler water and bacteria (decompose the dead
plants and animals)
• Benthic Zone – bottom of a body of water; inhabited by
decomposers, insect larvae, clams
• Lakes with large amounts of plant matter are eutrophic
(plants and algae grow in large quantities; bacteria break
down dead matter using up oxygen; diversity of species
decline).
Characteristics of Aquatic Ecosystems
• Plant and animal life depends on depth of water;
how fast water moves; amount of sunlight, mineral
nutrients, oxygen and temperature
• Contain several types of organisms, grouped by
their location and by their adaptations: plankton
(float near the surface and include phytoplankton,
zooplankton); nekton (free swimming organisms
such as fish, turtles, whales); and benthos (bottom
dwelling organisms such as mussels, worms,
barnacles)
• Decomposers are also a type of aquatic organism
Lakes and Ponds: Plant and Animal Adaptations
• •
Lakes, ponds, wetlands, rivers and streams make up
the various types of freshwater ecosystems
• •
Lakes, ponds and wetlands form naturally where
groundwater reaches Earth’s surface
• •
Littoral zone – where aquatic life close to shore is
diverse and abundant; nutrient-rich area (plants: cattails,
reeds: rooted in water, upper leaves and flowers above the
water)
• •
Further out, where there is still sunlight for
photosynthesis, live the phytoplankton (plants) and
zooplankton (tiny animals)
Lakes and Ponds: Plant and Animal Adaptations
• Deep lakes and ponds (too little light) contain a few
fish adapted to cooler water and bacteria
(decompose the dead plants and animals)
• Benthic Zone – bottom of a body of water; inhabited
by decomposers, insect larvae, clams
• Animals the live in lakes and ponds have adaptations
that help them obtain what they need to survive (ex:
water beetles: hairs under their bodies trap surface
air used to breathe during dives; whiskers on catfish:
sense food)
Lakes and Ponds: Plant and Animal Adaptations
• Lakes with large amounts of plant matter are
eutrophic (plants and algae grow in large
quantities; bacteria break down dead matter
using up oxygen; diversity of species decline).
Happens naturally over time, however,
eutrophication can be accelerated by runoff
that carries sewage, fertilizers, or animal
waste
Wetlands:
• Areas that are covered by water for at least part of the year
• Two main types:
• Marshes: contain non-woody plants (cattails)
• Swamps: contain woody plants or shrubs (trees and shrubs)
• Perform several important environmental functions: serve
as filters or sponges (absorb and remove pollutants from
water that flows through them); control flooding; serve as
spawning and feeding grounds for game fish; providing
homes for native and migratory wildlife (including
endangered and threatened species); vegetation traps
carbon which would otherwise be released back into the
atmosphere as carbon dioxide; produces commercial
products such as cranberries, blueberries, peat moss
Wetlands: Marshes
• Most freshwater wetlands are located in southeastern
US. Florida Everglades is the largest freshwater
wetland in the US; Everglades once covered 8 million
acres in S. Florida, today it covers less than 2 million
acres
• Several kinds of marches, each with its own
characteristics: brackish marshes (slightly salty); salt
marshes (saltier water)
• Occur on low, flat lands with little water movement
• In shallow waters, plants (reeds, rushes and cattail) root
to the bottom, leaves above the water year-round
Wetlands: Marshes
• Benthic zones are nutrient rich, contain
plants, numerous types of decomposers and
scavengers
• Waterfowl (ducks, grebes) have flat beaks to
sift through water; water birds (herons) have
spear-like beaks to grasp small fish and
frogs; attract migratory birds from temperate
and tropical habitats
Wetlands: Swamps
• Occur on flat, poorly drained land, near streams
• Dominated by shrubs or water-tolerant trees (red
maple, cedar, oak, cypress – depending on
latitude and climate)
• Mangrove swamps occur in warm climates near
ocean (more saline water)
• Ideal habitat for amphibians (green frog,
salamanders) and attract birds (wood ducks) that
nest in hollow trees; reptiles (alligator) are the
predator of the swamp and will eat almost any
organism that crosses its path
Threats to Wetlands
• Used to be considered wastelands (breeding grounds for
pesky insects) so people “improve” them by draining and
clearing them for farms, residential or commercial
development
• However, we now view them as purifiers (wastewater and
absorbers of hazardous flood waters)
• Vital habitats for wildlife for breeding (herons, storks,
other birds)
• Home to many amphibians and reptiles (alligators,
crocodiles)
• Federal government now prohibits the destruction of
wetland areas
4.7 Rivers
• Originate from snowmelt in mountains
• Headwaters-water is usually very cold and highly
oxygenated; runs swiftly; shallow
• As it moves down the mountain, it broadens; water
is warmer, loses oxygen and flows more slowly
• Characteristics vary depending on land and climate
• Runoff wash nutrients and sediment from
surrounding land into a river, thus affecting growth
and health of organisms in the river
Rivers: Plant and Animal Adaptations
• Near headwaters, mosses anchor themselves to the
rocks
• Mayflies use hooks on their legs to cling to any stable
surface
• Trout (streamlined bodies, powerful swimmers) and
minnows are adapted to live in the cold, highly
oxygenated water
• Downstream – catfish, carp (adapted to glide over river
bottom) prefer warmer, calmer water
• Freshwater aquatic plants (crowfoot) set roots in soil;
many have arrowhead shaped leaves depending on
the speed of the water
Threats to Rivers
• Industries use river water in manufacturing processes
and as a receptacle for waste
• People have used rivers to dump sewage and garbage
• These practices have polluted the rivers with toxins;
killing river organisms and making the fish inedible
• Runoff from the land is putting pesticides and other
poisons into the rivers and coats the riverbeds with
toxic sediments
• Dams alter river flows and destroy fish habitats
4.8 Marine Ecosystems
• The oceans of the world contain a wide
variety of plants and animal communities
• The types of organisms present in marine
ecosystems depend on temperature and
the amount of sunlight and nutrients are
available.
Coastal Wetlands
• Land areas covered by salt water for all or
part of the time are known as coastal
wetlands
• Provide habitat and nesting areas for fish and
wildlife
• Also absorbs excess rain, protects areas
from flooding, filters out pollutants and
sediments, and provides recreational areas
for boating, fishing and hunting
Estuaries
• Many coastal areas form in estuaries
• An ecosystem where fresh water from rivers
mixes with the salt water from the ocean; as the
two bodies of water meet, currents form and
cause mineral rich mud and nutrients to fall to the
bottom and become a nutrient trap; constantly
getting fresh nutrients
• Among the most productive ecosystems; contain
plenty of light, nutrients for plants
Estuaries: Plant and Animal Adaptations
• One week each spring, huge snowshoe crab crawl out
of the ocean onto the beaches of the Delaware Bay to
mate and lay their eggs. Shorebirds wait for them and
millions of migrating birds will stop there to gorge on
the eggs
• Rivers supply nutrients washed from the land; water is
shallow; sunlight reaches the bottom; in shallow areas,
marsh grass grows
• Can support large amounts of plants, phytoplankton
and zooplankton which provide food for larger animals
(fish, dolphins, manatees, seals, other mammals)
Estuaries: Plant and Animal Adaptations
• Oysters, barnacles, clams live anchored to marsh
grass or on the bottom and filter algae and debris out
of the water
• Organisms can tolerate variations in salinity as the
content of the water varies as fresh water and salt
water mix (tides)
• Provide protected harbors, access to oceans and
connections to rivers, as a result, many of the world’s
major ports are built on estuaries; six of the ten largest
urban areas in the world (Tokyo, New York, Shanghai,
Buenos Aires, Rio de Janeiro, Bombay)
Threats to Estuaries
• Were used as dumping grounds, filled and then
used as building sites, occurred extensively in
California; now, plans are to restore them to
estuary wetlands
• Industrial waste (toxic chemicals), sewage,
agricultural runoff containing pesticides and
fertilizers have damaged estuaries
• Most of the pollutants will break down over time,
but estuaries cannot cope with the large amounts
produced by dense human populations
Salt Marshes
• Dominate much of the shoreline of the Gulf of
Mexico, Atlantic Coast of US; absorb pollutants and
protect inland areas
• Develop in estuaries where rivers deposit their load
of mineral rich mud; support clams, fish, and
aquatic birds
• Acts as a nursery for shrimp, crabs and fish when
they are small; later to be eaten by larger fish or
caught by commercial fisheries
Mangrove Swamps
• Located along coastal areas of tropical and
subtropical zones; help to protect the coastline
from erosion, reduce damage from storms
• Mangrove trees dominate the mangrove swamps;
grow partly submerged in the warm, shallow,
protected salt water
• Provide breeding and feeding grounds for about
2000 animal species
Coral Reefs
• Limestone islands in the sea that are built by coral
animals called polyps (very slow growing);
thousands of species of plants and animals live in
the cracks and crevices; among the most diverse
ecosystems on Earth
• Corals live in only warm salt water; a lot of light for
photosynthesis; shallow, tropical seas
• Only outer layer of coral is living
Coral Reefs: Animal Adaptations
• Coral Polyps are predators that never chase their
prey; use stinging tentacles to capture small
animals that float or swim too close
• Provide habitats for a variety of tropical fish,
snails, clams, sponges
• Parrotfish have teeth fused into their beaks which
they use to scrape algae and corals off the reefs
to eat
Threats to Coral Reefs
• Coral Reefs are productive but fragile ecosystems
• Estimated 27% of coral reefs are in danger of
destruction from human activities
• If they get too hot or too cold, or fresh water
drains into the water surrounding the reef, corals
cannot produce limestone needed to survive
• If it is too muddy, too polluted, too high in
nutrients, algae will die or grow out of control and
smother the corals
Threats to Coral Reefs
• Oil spills, sewage, pesticides, silt runoff are
linked to coral-reef destruction
• Overfishing can devastate fish populations,
upsetting the balance
• Coral reefs grow very slowly and cannot
repair itself after being destroyed by careless
divers, shipwrecks, anchors, people breaking
off pieces
4.9 The Ocean
• Covers nearly ¾ of Earth’s surface
• Plants only grow where there are nutrients and
light; most life is in shallow water around the
edges of continents; abundant with plants and
animals in these areas
• Open ocean, phytoplankton grows near the
surface (sunlight) if there are nutrients; one of the
least productive of all ecosystems
• The depths of the ocean are dark and most of the
food consists of dead organisms (falling from the
surface)
Ocean: Plant Adaptations
• No flowering plants except around the
edges
• Food for herbivores in the open ocean are
phytoplankton (floating by being buoyant or
having long spines; whip-like flagella; oil
droplets)
• When they die, they sink to the bottom
Ocean: Animal Adaptations
• Smallest herbivores are the zooplankton (jellyfish, tiny
shrimp, fish larvae) which live near the surface; others
(oysters, lobsters) live at the bottom
• Dozens of fish, as well as seals and whales (mammals) feed
on plankton
• Evolved sleek, tapered shapes for moving through dense
water; silvery color (protective camouflage); buoyancy
devices to stay at one level (sharks –oily livers; bony fish –
gas-filled swim bladders; mammals – lungs
• The depths of the ocean are perpetually dark; decomposers,
filter feeders and organisms that eat them live here
• Poor visibility at these depths so organisms use “light” to
communicate (luminous) or sound (whales – “songs”;
dolphins – clicks and calls
Threats to the Ocean
• Pollution – comes from the land; same as the pollutants on
the land (fertilizers causing toxic algal blooms; industrial
waste; sewage discharged into rivers, particularly from
nuclear power plants)
• Overfishing and some fishing methods have destroyed
fishing grounds, nets entangling every living thing bigger
than the holes (most of the catch are not used and are
thrown back, dead); marine mammals drown; fishing lines
are discarded in the ocean and strangle fish, seal
• All of these things are reducing reproduction thus
endangering many species
Polar Ecosystems
• Ice covered North and South Pole are
considered marine ecosystems because most of
the food supply is phytoplankton
• South Pole lies on the continent of Antarctica and
is covered with a permanent icecap (melts only
around the edges); North Pole is not on land at
all; lies in the Arctic Ocean, frozen into a huge
iceberg throughout the year with little icebergs
floating around it
The Arctic
• Relatively shallow; rich in nutrients; supports
large populations of plankton
• This provides food for a diversity of fish, whales,
ocean birds (who prey on the fish), seals
• The birds and seal bear their young on the ice;
they provide food for the few humans that live
there and for the polar bear
The Antarctic
• Only continent never colonized by humans
• Used mainly for research on the unusual animals
that live there
• Only a few plants live there
• Plankton forms basis of the food chain; feeds fish,
whales, penguins
Threats to Polar Ecosystems
• Contains reserves of minerals (oil) whose
extraction would disrupt this large untouched
ecosystem
• Conservationists want it made into a world wildlife
refuge
• Main threat is tourism (garbage left behind, does
not decay because it is so cold)
• They are working to solve that problem