Algae comprise a diverse group of typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are generally...
MacrophytesLast Updated on 2014-10-01 11:04:52
Macrophytes are the conspicuous plants that dominate wetlands, shallow lakes, and streams. Macroscopic flora include the aquatic angiosperms (flowering plants), pteridophytes (ferns), and bryophytes (mosses, hornworts, and liverworts). An aquatic plant can be defined as one that is normally found growing in association with standing water whose level is at or above the surface of the soil. Standing water includes ponds, shallow lakes, marshes, ditches, reservoirs, swamps, bogs, canals, and sewage lagoons. Aquatic plants, though less frequently, also occur in flowing water, in streams, rivers, and springs.
Macrophytes constitute a diverse assemblage of taxonomic groups and are often separated into four categories based on their habit of growth: floating unattached, floating attached, submersed, and emergent. Floating unattached plants are those in which most of the plant is... More »
LichenLast Updated on 2014-08-28 00:58:22
The lichen has traditionally been referred to as a prime example of a symbiotic relationship. Each lichen consists of an intimate association between a fungus and a species of algae. The algae within the lichen photosynthesizes, providing food for both symbionts. The fungus protects the alga from harmful light intensities, produces a substance that accelerates photosynthesis in the algae, and absorbs and retains water and minerals for both organisms. There is physiological and ultrastructural evidence that suggests the fungus parasitizes the algae in a controlled fashion and, in some instances, actually destroys the algal cells. There are about 25,000 species of lichens known and they are capable of living in environmental conditions that kill most other forms of life. The number of aquatic lichens is limited as most live under the blazing sun often on bare rocks. Aquatic... More »
Backyard pondLast Updated on 2014-06-25 17:01:23
A pond or water garden will likely become the focal point for all your backyard conservation.
Backyard ponds and water gardens are for birds, butterflies, frogs, fish, and you and your family. These ponds are typically small, sometimes no larger than 3 to 4 feet in diameter. They may be built in barrels or other patio containers. Water is effective in drawing wildlife to your backyard. It is also a natural, relaxing, and scenic addition that can provide interest and enjoyment.
Consider locating your backyard pond where you can see it from a deck or patio. Have it blend in with its natural surroundings. Elevate the soil around the pond slightly so that excess water will flow away from the pond, not into it. Make sure that any drainage from the pond is away from your house. Plan to landscape around the pond to provide habitat for frogs and birds that need land and water.... More »
Engelmann, Theodore WilhelmLast Updated on 2014-06-15 19:05:28
Theodore Wilhelm Engelmann (1843 - 1909), a German physiologist, showed that the light reactions of photosynthesis, which capture solar energy and convert it into chemical energy, occur within the chloroplasts and respond only to the red and blue hues of natural light. His experiments involved a modified microscope condenser that allowed him to expose parts of photosynthetically active cells of the green alga Spirogyra to a thin ray of light. His aim was to discover which components of the cell functioned as light receptors.
Energy Luminaries: Theodore Engelmann (National Science Teachers Association)
Photosynthesis: The Light Reactions (Massachusetts Institute of Technology)
Photosynthesis: The Dark Reactions (Massachusetts Institute of Technology)
DiatomiteLast Updated on 2014-06-15 18:57:41
A diatom is an organism that is a member of the phylum of algae called Bacillariophyta. There are about 60,000 species of these algae presently known. Experts estimate that there are more likely 600,000 to 6,000,000 species in total!
Diatoms are single-celled (unicellular) organisms that live as individuals or in groups called colonies. They exist in all the waters of the Earth, both salt and fresh. They form shells made out of silica (the mineral name of this silica is opal) which they extract from the water. Their microscopic shells are very intricate and beautiful and have rightly been called "the jewels of the sea." Diatoms are very abundant and provide food for many aquatic animals.
When diatoms die, their silica shells accumulate on the floor of the body of water in which they lived. Thick layers of these diatom shells have been fossilized (that is, preserved)... More »
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