Lakes


This is a smaller lake. It has vegetation around it's shoreline and some water plants going out from shore a little distance. It is shallow around the shoreline but has locations where it is deep. Deep would be areas of the lake where light does not penetrate all the way to the bottom. You can not tell how deep a body of water is by looking at the surface. Some lakes are composed of clear water while other lakes may be composed of water that is turbid. A turbid body of water could be tea color or it could look like pea soup. Just because a lake is not clear does not mean it is polluted.

What kinds of things live in a lake?

Plants: there are a number of different types of plants that live in a lake. They live from the surface down as far as light penetrates. Most people would recognize cattails (Typha) growing around the shoreline. the waterlily is another water plant that people associate with lakes. Many plants have their leaves submerged. One such plant is pondweed. Most of what you would see of this plant would be only the flower spike sticking out of the water.

Lake challenge:

  1.    Living things have a job or function in their environment. What is the job or function of water plants in a lake?

  2.    Describe two other water plants that live in a lake

 

Algae: are another photosynthetic group of organisms that live in water. Some will attach to objects, but others will float on or near the surface of the water. There are a number of different groups of algae. Blue-Green Algae are a group in which the cells lack nuclei, the pigment is scattered, and have a slimy coating. The other groups are Green Algae, Stoneworts, Euglenoids, Dinoflagellates, and Diatoms. Algae form the base of the food pyramid in lakes and ponds.

Lake challenge:

  1. You are to find and describe a Green Algae and a Dinoflagellate.

  2. Do you believe this group has the same function or a different function than the water plants. Explain!

Helpful links to find information about algae:

Algae link 1
Algae link 2

Protozoans: Another group of organisms living in water are the Protozoans. They are microscopic in size so are almost impossible to see without the aid of a microscope. Even though they are very small, they play a key roll in their environment. The protozoans plus the algae form what we call plankton. The protozoans make up a group called zooplankton while the algae make up the phytoplankton. A few protozoans we have used in school before are, euglena, volvox, amoeba, and paramecium. The plankton form the base of the food chain in the fresh water ecosystem.

Lake challenge: 5. Your assignment is to find two protozoans, draw a picture of each and describe them.

Protozoan link 1
Protozoan link 2

Rotifers: rotifers are a group of organisms that are found only in fresh water. If you look at a sample of pond water, you would probably find many rotifers in your sample. Some rotifers feed on algae and then themselves are eaten by worms and crustaceans. As we move up to larger animals we find worms and leeches, and then crustaceans. You would also be able to find a number of different insects that live part of or all of their lives in water. One of the more famous insect that spends the first part of it's life (the larva stage) in water is the mosquito.

Lake challenge: 6. find an insect that spends part of its life cycle in water and describe it.

Rotifer link 1
Rotifer link 2

 

Larger Animals

We could spend a year or more going through the larger animals such as; clams and snails, frogs and salamanders, all types of reptiles and birds. I believe when people think of lakes they think of fish. We put fish at the top of the food chain of those organisms living IN a lake. There are all kinds of fish living in lakes. Some of the more well known are; bluegills, perch, catfish, bass, walleyes, and northern pike. There are many more. We have gone through a number of organisms that live in and depend on fresh water. All of these organisms are connected, one living off  the other. They form a food chain or better yet, a food web.

Lake challenge: 7. You are to draw up a food web using the organisms we have gone through on this page. Draw this food web by placing pictures or drawing of these organisms and showing their relationship by connecting them by lines.

You can download a copy of the above questions by going to Worksheet.

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