The Indians and early American explorers used to look for animal signs to determine whether an area was worth settling. Their survival depended upon the diversity of the community and understanding the environment around them.
In this class, you will learn about what plants and animals need to survive, how all living things relate to each other and how communities change over time. But first, we need to know one small, minor, insignificant little thing. Okay, maybe it’s not so insignificant:
The place that a plant or animal would naturally live is called a habitat. All plants and animals have their own place where they can live and grow, and which is suited for their needs. For example, you don’t normally find water lilies in the desert; similarly you don’t normally see a cactus in the middle of a Midwestern corn field. Plants and animals live in the places where they can best survive. (This is the central idea for “Communities”, one of the seven Concept Paths.)
Habitats vary widely depending upon the type of plant or animal; however all plants and animals have the same basic needs. They are:
Animal Habitat Requirements:
- Air (Oxygen)
Plant Habitat Requirements:
- Air (Carbon Dioxide)
Without these basic needs being met, a plant or animal cannot survive. If any one of the five basic requirements for life is missing or is in too short of supply, the plant or animal dependent upon the habitat will die. Notice the similarities between plants and animals: they both need air (though different types), they both need water and they require space to grow.
Do these requirements apply to human beings? (Yes.) Is lack of clean air a problem for humans? (In some places, yes.) How about food? (Yes. People are staring to death all over the world.) Shelter? (People in America die from exposure every year.) Space? (Not yet, but there is some concern that the world may run out of room for humans.) Clean water? (Wait until you study “Environmental Engineers”…)
A place where many plant and animal habitats overlap is called a community. A community s a place where plants and animals interact, each with a specific job, or role. Roles within most communities include:
1. Producers: plants which takes in the sun’s energy, air, water and
nutrients from the environment and convert it into food. (The
basis for all food chains.)
2. Consumers: animals which eat other living things for food.
3. Decomposers: plants and animals which break down dead
matter, returning vital nutrients to the soil.
All roles are important within the community. Very few communities can survive without all of these roles, though deep ocean trenches can do without Producers (bacteria is the basis for their food chain). This is an exception to the rule, however.
Not only do all plants and animals have a role (job) within the community, but they must also deal with other members of the community. Think about your community (the city you come from. Does everyone get along with everyone else? (Not usually.) Are some people friends, though? (Yes.) Are there some people you don’t know? (If your community is large enough…) The same goes for all other communities.
1. Mutualism: two organisms depend upon each other for survival.
2. Commensalism: two organisms coexist; one organism benefits without helping or harming the other.
3. Parasitism: one organism depends upon another for food, this relationship harms the host.
4. Predator/ Prey: one organism eats another organism as food.
Everything depends upon each other. It’s easy to see how two organisms helping each other depend upon each other, but what about one organism that sucks on another? (Parasitism.) By killing off members of a community, parasites are actually helping! How? (They control the population and prevent too many inhabitants from living in one area at one time.)
We to call too many of one organism in an area “overpopulation”. Predator / prey relationships and parasitism help to prevent overpopulation, helping maintain the balance of a community. Without these roles, a dominant species would quickly take over, destroy the food chain and wreck the habitats of other plants and animals.
The more diversity in a community, the more stable it is. In other words, the more variety of plants and animals, the less likely it is to be damaged by outside forces. If an animal can only eat one type of plant and that plant dies out in the area, what happens to the animal? (It starves.) If an animal will eat many different types of plants, but its favorite type dies out, what happens to the animal? (It adapts by eating another type of plant.)
Major disruptions (pollution, fire, climatic changes etc.) will cause one of three responses from each member within the community:
1. Adaptation of the organism.
2. Movement to a new area.
3. Extinction (death).
This leads us to talking about what things eat. A very simple topic…
When we are talking about predator / prey relationships within a community, we are talking about two different types:
Food Chain: Official Definition: Food consumption patterns link plants and animals
together in a chain.
Plain English: The path of the sun’s energy through all living things
How it Works: Sun gives energy to plants, animals eat plants for energy, larger animals
eat smaller animals for energy, etc.
Sample Food Chain:
Sunà Grassà Grasshopperà Spiderà Frogà Snakeà Bird
Important notes on food chains:
1. Energy is lost at each stage of the chain. Not all the energy given by the sun is received by the plants. Not all the energy within the plants reaches the animals. Not all the energy of the small animals reaches the large animals.
2. The more “efficient” food chain is the one with the shortest links between the producer (green plant) and the top of the food chain. The fewer the steps, the less energy lost.
3. The sun, though not always shown, is always the bottom of a food chain. All energy used by living things comes from the sun.
4. Food chains are very fragile. If one link in a food chain is “damaged” in some way, the rest of the food chain must adapt or die.
Official Definition: the overlap between several food chains.
Plain English: the overlap between several food chains.
How it Works: animals are given multiple choices for food sources; this makes the
community much more “stable” and less likely to die off with the
extinction of a single species.
Sample Food Web:
Important notes on a food web:
1. Note the overlap. The frog eats not only the spider, but the grasshopper as well. This is the main difference between a food chain and a food web. In a food chain, we would only be told that the frog would eat the grasshopper, then we would find out what eats the frog.
2. Diversity provides for success! The more overlaps, the stronger the food web. The stronger the food web, the less likely it is that everything will die if one species becomes extinct. (Bonus Question: What’s the weakest link of the chain? (The grasshopper.) Why? (Because if it dies, there is nothing in this web that can eat the grass. The food chain will die) Do you see why webs are stronger than chains?
3. Energy flow within the food web can become very complex, depending upon the number of steps it takes to reach the top of the food chain.
For our canoe trip, we will be traveling from Long Lake to Mud Lake. Between the two, you will see a large difference. Long Lake is definitely a lake, but what about Mud Lake? Is it a lake or is it a, pond? How can we tell the difference?
- Quiet body of water (little movement.)
- Little wave action
- Affected by air
- Temperature constant throughout.
- Mud bottom
- Plants growing over most of it
- Less Water
- Marsh land surrounding
- More movement (Currents, boats, etc.)
- Wave action can vary due to weather
- Air has little effect except on the surface
- Warmer in shallows, cooler in deep water
- Bottoms can vary throughout the lake
- Plants usually grow only around the edges
- Water amount is larger than a pond’s
- Water can reach great depths
- Definite shoreline. Well defined
In a pond or a lake, there are definite places where plants and animals live. Remember when I mentioned that plants and animals live in places where they are most suited? Well, in a pond or a lake, there are many different types of habitats. You wouldn’t expect to see a three foot long Muskie hanging out in three inches of water, would you? (No.) Also, you wouldn’t expect plants which need to reach above the water for sunlight to plant themselves in eighty feet deep water, would you? (Of course not.) Each plant and animals lies where is can best survive. (By the way, if you are the first person to come up and show this sentence to me during staff training, I will get you a pop! (Limit one per season. Void where prohibited.)
1. Emergent Zone
a. Near shoreline.
b. Plants have roots.
c. Plants extend above the water line.
d. Home to a wide variety of animal life. Can also be called a
f. Plants are “emerging” from the water! Hence the name, guess…
2. Floating Zone
a. Further from shore.
b. Plants float on the surface. (Duh!) Common plants are duckweed
and lily pads.
d. Bottom plants are scarce (sunlight blocked by floating plants
e. Home to minnows and water insects.
3. Submerged Zone
a. Further from shore than Floating Zone.
b. Plants barely break the surface, if at all. (Gee! Is that why we
call them “sumerged”?)
c. Larger fish, turtles, and other animals.
d. Less “visible” plants (compared to Floating Zone).
e. Fewer water insects.
4. Open Water Zone
a. Deep water
b. Temperatures tend to be colder, especially further down.
c. Lack of vegetation
d. Large fish, though fewer other animals.
Over time, communities (also called ecosystems) can overlap. Plants grow in water, die, decay, and form new soil. This soil adds to the bottom of the lake, thus making it shallower. As this process continues over time, it speeds up. Less water promotes more plant growth. More plant growth speeds up the soil production. This cycle by which lakes can fill in over time is defined by two main words:
Succession: a gradual change in the composition of an ecosystem as competing
organisms and plants alter the environment.
Encroachment: the act of one ecosystem invading upon another’s area and space.
What’s the difference? Encroachment is one ecosystem moving into another. Succession is a process by which one ecosystem is converted into another; this is a process which, once complete, will leave no obvious evidence that the other ecosystem had ever been there. The area where the two separate ecosystems overlaps is called an “ecotone” .
E.g. Lakeà Plant Growth àMarsh à Continued Succession à Forest
Why do we bring this up? Take a look at Mud Lake! We’ll discuss that more when we get there (I’ll give you a hint, though: there is a reason that I put this section in here, rather than a sheer desire to continue typing.)
Discussion Info (see above): Time: 30 40 minutes
2. Needs of living things.
3. Communities and roles of living things.
4. Food chains.
5. Food webs.
6. Pond versus lakes.
7. Aquatic habitats.
8. Succession and encroachment.
Bathroom Break: Time: 10 minutes
How to Canoe: Time: 20 minutes
· No standing up in the canoe.
· Always wear a life jacket.
· Ask the instructor before trading places
· No dunking, tipping or splashing.
· To turn to the right=both paddle on left
· To turn hard right = back person “digs in” on right side
· To turn to the left = both paddle on right
· To turn hard left =back person “digs in” on left side
· To go straight =paddle on opposite sides
*Note: Back person controls the steering and direction!
· Have all students practice on land before hopping into the canoes.
· Do NOT short change the instruction time. It will be a long trip if you do!
· Have teachers and/or staff in both lead and last canoes.
· Have all canoes wait at bridge before proceeding.
Canoe Trip: Time: 1/2 to 2 hours
Make sure to point out areas of succession. Review habitat requirements. Ask what animals would live in what habitat. This is to be an outdoor laboratory to reinforce the ideas taught in the class.
Community: an area where many different plants and animals live and interact
Consumers: animals which eat other living things for food.
Decomposes: plants and animals which break down dead matter, returning vital
nutrients to the soil.
Encroachment: the act of one ecosystem invading upon another’s area an space.
Food Chain: the path of the sun’s energy through all living things.
Food Web: the overlap between several food chains.
Habitat: basic life giving conditions needed for survival
(animals: food, air, water, shelter and space )
(plants: air, water, space, sunlight, minerals)
Predator / Prey: the relationship between an anima and the organism it eats for food.
Producers: plants which takes in the sun’s energy, air, water and nutrients from environment and convert it into food. The basis for all food chains.
Succession: a gradual change in the composition of an ecosystem as competing organisms and plants alter the environment.
Ecosystem: an area where living things interact. (Also called a “community”)
Ecotone: an area where two ecosystems overlap.
Extinction: the end of a species in a given area.