COS L6.2 Describing the grouping of organisms into populations,
communities, and ecosystems.
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What are Ecosystems? Ecosystems vary in size. They can be as
small as a puddle or as large as the Earth itself. Any group of
living and nonliving things interacting with each other can be
considered as an ecosystem.
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Smaller Parts of an Ecosystem Within each ecosystem, there are
habitats which may also vary in size. A habitat is the place where
a population lives. A population is a group of living organisms of
the same kind living in the same place at the same time. All of the
populations interact and form a community. The community of living
things interacts with the non-living world around it to form the
ecosystem.
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Vocabulary for Ecosystems ecosystem all the living and
nonliving things in an area habitat an environment that meets the
needs of an organism community all the populations of organisms
living together in an environment population all the living
individuals of the same kind living in the same ecosystem organism
a living thing ecosystem all the living and nonliving things in an
area habitat an environment that meets the needs of an organism
community all the populations of organisms living together in an
environment population all the living individuals of the same kind
living in the same ecosystem organism a living thing
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Parts of an Ecosystem organism population community habitat
ecosystem
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BrainPop Click here to learn more about ecosystems from
BrainPop. Click here
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DESERT ECOSYSTEMS
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Desert Ecosystem Deserts are full of interesting questions. How
can anything survive in a place with hardly any water? Why is it so
dry to begin with? Turn and talk to your neighbor about these
questions.
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Desert Ecosystems You can find at least one desert on every
continent except Europe. Each desert is different in some way, but
they all have one thing in common. In order for an area of land to
be considered a desert, it must receive less than 10 inches of
water a year. Image from www.cjreport.com
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Desert Ecosystems Clouds are scarce in deserts. Without clouds,
there can't be rain, snow, or any other precipitation. Clouds also
shade the land, so without them, the desert gets mighty hot as the
Sun beats down during the day. At night, the desert can become very
cold, because there isn't moisture in the air to hold onto the
heat
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Geology of Deserts The geology of each desert is unique. Some
deserts have sand dunes - great waves of sand weathered from rock,
that move over time as wind blows the sediment. Other deserts have
no dunes but instead have unique rock formations carved by wind and
streams that only flow at times when there is moisture.
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Desert Sand Dunes The Sahara Desert Image from:
davidwallphoto.com
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Desert Sand Dunes The Sahara Desert Image from:
www.art.comwww.art.com
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Rock Formations in Deserts Arizona
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Rock Formations - Arizona
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Ecosystems - Deserts With little water, can plants and animals
survive in this ecosystem? Image from: 3.bp.blogspot.com
Slide 19
Ecosystem Plants and Animals Surprisingly, there are many
species of plants that survive in the desert. We will learn about
some of the most common animals and plants that can be found in a
desert ecosystem.
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Desert Plants The most famous desert plant is the cactus. There
are many species of cacti. The saguaro cactus is the tall, pole
shaped cactus you see on television. The saguaro can grow up to 40
feet tall. It can hold several tons of water inside its soft
tissue. Like all cacti, the saguaro has a thick, waxy layer that
protects it from the Sun.
Slide 21
The Saguaro Cactus Courtesy of Corel Photography Photo:
Copyright Gary Minniss
Slide 22
Horned Lizards (Toads) Of all the North American lizards,
Horned Lizards are the most fearsome-looking and distinctive by
virtue of the pointed, protruding "horns" above their eyes. Image
from desertsusa.com
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Horned Toad Lizards The numerous species of Horned Lizards have
very wide, flattened, toad-like bodies. The tail is short but broad
at the base. In most species, the back of the head and temples are
crowned with a prominent row of sharp, pointed horns. The tail and
sides are fringed with sharp spines. On some species the sides are
adorned with a double fringe of spines. On the back, there are rows
of short conical spines.
Slide 24
Horned Toad Lizards To the uninitiated, their dragon-like
appearance is quite frightening. The squat form and head armor has
given rise to the name "hornytoad," "horned toad" and "horned
lizards." However, since there is a true toad with horns, it is
best that we speak of this genus as the "Horned Lizards." Their
colors are pleasing. The back and head are soft desert gray. The
markings are in pastel shades of tan, brown, red or yellow. The
underparts are pale, yellowish gray. The overall colors are
generally close to the predominant color of the soil. Color changes
from light to dark (or reverse) can occur within a few
minutes.
Slide 25
Range and Habitat of Horned Lizards Horned Lizards are found
only in the western portions of the United States and Mexico. There
are 14 recognized species. They range from Arkansas to the Pacific
Coast, and from British Columbia south to Guatemala. These lizards
are creatures of hot, dry, sandy environments. Some of the species
inhabit the deserts proper where the sun, beating on the arid
landscape, produces ground heat that is almost unbearable to
humans. Others enter mountainous areas and are found as high as
10,000 feet.
Slide 26
Habitat of Horned Lizards Regardless of where they occur, there
is a similarity in their habits. In the fall, they hibernate by
burying themselves in the sand. They emerge in the spring when the
sun's rays have reached a certain temperature. The first few hours
of the day are spent basking, usually flattened against a rock or
on slanting soil, so their back is exposed to the sun. At times,
while warming up, they may flatten and tilt their bodies toward the
sun to obtain maximum radiation.
Slide 27
Habitat and Food Sources of Horned Toads As soon as their body
temperature rises to a specific degree, they commence foraging for
food. As the heat of the day increases, they become more active.
They feed on slow-moving, ground-dwelling insects, spiders, sow
bugs, an occasional tick and even items as large as the butterfly.
and sphynx moth larvae. Ants seem to be their major food source.
They do not pursue their victim hastily, like some lizards, but
poise over it and methodically take it, in toad-like fashion, with
a flick of their long, sticky tongue. The toad-like action ceases
if disturbed, for they will flee as rapidly as a startled mouse.
Video Link: Horned Toads and Ants
http://www.desertusa.com/video_pages/ants_movie.html
http://www.desertusa.com/video_pages/ants_movie.html
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Slide 29
Javelina The javelina is the only wild pig in North America. It
looks exactly like a real pig except a little bigger. It is a
grizzled blackish-gray color with a yellowish band which runs under
the neck. Javelinas live in the canyon area of the desert. They
live there because it is bushy and there are water holes
everywhere. They need the bushes for the shade and they need lot's
of water to live. The javelina eats cacti, grass, bulbs, berries,
flowers, mushrooms, and fruit, which is easy for them to get in
their habitat.
Slide 30
Javelina The javelina always travel and live in groups. The
female gives birth to twins about once a year. Her young travel
with the group their whole life until they die. No new members are
ever accepted into the group unless they are born into it. The
javelinas have a very good nose. That can have its advantages if
there is a predator around. They also look for food in groups so if
they're attacked they can fight back in numbers.