Created by Mr. Hemmert

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L6.2 Describing the grouping of organisms into populations, communities, and ecosystems.

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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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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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ecosystem – all the living and nonliving things in an area
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habitat – an environment that meets the needs of an organism
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community – all the populations of organisms living together in an environment
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population – all the living individuals of the same kind living in the same ecosystem
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organism – a living thing

organism

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Click here to learn more about ecosystems from
BrainPop.

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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?
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Turn and talk to your neighbor about these questions.

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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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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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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.

Image from: davidwallphoto.com

Image from: www.art.com

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With little water, can plants and animals survive in this ecosystem?
Image from: 3.bp.blogspot.com

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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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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.

Courtesy of Corel Photography
Photo: Copyright Gary Minniss

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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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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.

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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."
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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.

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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.

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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.

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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

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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.

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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.