Thursday, August 23, 2012

Science Week 3: Algae and Seaweed

new links added after publishing will be posted at bottom of post and highlighted in red...

We had fun with our mushroom lessons, but in the interest of moving along with school and not bunny trail terribly far this year, it's time for algae lessons.

Our verse this week for science is Genesis 1:31a...And God saw everything that He had made, and, behold, it was good.

Our notes this week:

  • Algae belong to a plant division called Thallophytes,. There are over 80,000 known plants included in this division, and our study is on the algae plants. Algae of this type have single cells that form the main body, or thallus. Some appear to have roots, stems, and even leaves, but these parts do not function as true roots, stems, or leaves.  Thallophytes have no tubes through which sap moves.
Classification of microorganisms
  • Algae plants contain cholorphyll. Sunlight or indirect light allows the cholorphyll to combine carbon dioxide from the air with water and minerals to produce food for the plant. This is called photosynthesis, which means "to put together in light". Because they need light, algae grows in shallow water, or in the upper layers of deeper water. Links on photosynthesis here.
Common names used to refer to algae include "seaweed" and "pond scum."
  • Many algae are covered in gel-like layers. Separate plants form sheets and clumps because their outer walls cling together.
  • Algae species (there are over 10,000 different kinds) are divided into four classes based on their, green, brown, and red.
Blue-green algae is found in salt and fresh water and cannot be seen without a powerful microscope. They can withstand heat up to 200*, drying, and freezing. Some species have been dried and re-hydrated after 70 years and were still alive. These plants grow on land if they have a water supply. Several rock terraces at Yellowstone National Park are colored by algae. Many simple blue-green algae increase by cell division. Each cell divides, grows larger and divides again. Entire colonies form, break apart, and continue to multiply.

Almost all fresh water is home to one or more species of green algae. Common names for these plants are water moss and pond scums. The smallest of these algaes are found among desmids which coats sticks, shells, and other objects. The bright green hairy growth in water tanks or streams.
Sea lettuce - Ulva lactuca/Blue Ocean Society preview preview

Brown Algae live mostly in the ocean or on rock seashores between low and high tide marks.Their green cholorphyll is covered completely by purple-brown or golden-brown coloring. The largest brown seaweed is kelp that can grow up to 200 feet. One of the largest areas of brown algae, sargassum or gulf weed, is found in the Sargasso Sea area of the North Atlantic Ocean. The Sargasso Sea is a large, calm area of ocean amidst swirling currents of the Gulf Stream, which encompasses nearly 2 million square miles. It is estimated there is approximately 10 million tons of floats algae there, providing floating homes to crabs, shrimps, small fishes, and various other animals.
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Another brown seaweed known as rock weed, grows along rocky shores and forms a thick cover.  This leathery plant can be up to 2 ft. long and usually has 2 branches. Brown algae grows only in salt water.
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Red Algae are always found in ocean water. They prefer the warm temperate climate, but can be found in tidal pools and along coral reefs from polar waters to the tropical regions. They can grow at a deeper depth than the brown seasweeds. Many of these are finely branched and feathery. The green color of their chlorophyll is covered by bright red, purple, or shades of violet and rose.
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Edible algaes...the people of Japan, China and Hawaii use more than 100 different kinds of seaweeds as food. In Japan they cultivate beds of algae covering 1000 acres and harvested 3-4 months later. In the United States, agar-agar from seaweed, is used to thicken soups and sauces, ice creams and desserts, even pastries. Canned fish is improved by adding agar-agar. Chlorella, when dried, tastes much like raw pumpkin or raw lima beans. High in vitamin value, chlorella is more than 50% easily digested protein.

Some links:
Here is a lab lesson on pond water 
Microbial Life has some pages/information on Red Tides, or red algae bloom
**Learn for Your Life has several nice pages of activities and experiments covering several topics
Smithsonian Institute pages on algae research

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