Diatoms

1
Diatoms

• By Jared Williams
• Andre Pierre-Louis
• Chris Terrell

2
Appearances

• Diatoms can form small colonies, and filaments
  have been seen to measure over two feet. The size
  of these very diverse micro-organisms varies
  greatly. There is a yellow tint that can be seen
  due to photosynthetic plastids. When observed as
  larger masses, the color takes on a darker color,
  often deep brown or black. Some diatoms also have
  a blue or green color, but these are the
  exceptions.

3
Habitat

• Diatoms are found in both fresh water and salt
  water. There in fresh water habitats mostly in
  the spring and fall months. Not only do diatoms
  live in streams, lakes and other bodies of fresh
  water, but they can be found on the rocks,
  plants, and mud that is nearby or at the borders
  of the water.

4
Ocean Location

• Ocean Location Diatoms can be found within the
  range of the tides and water that covers the
  ocean bottom regions. They are classified as
  either pelagic (existing within the water column)
  or benthic (existing on the seafloor).

5
Microscopic Appearance

• Cell Wall The cell wall is composed mostly of
  silica (SiO2). This term refers to the frustules
  and the organic stuff that covers the valves and
  girdle.
• Frustules The frustules contain two valves that
  fit within each other (one valve is smaller than
  the other. The frustules can have all different
  shapes symmetrical as well as asymmetrical.
• Epitheca This term is used to refer to both the
  larger older valve of the frustules as well as
  the girdle elements that are connected with it.

6
Growth

• The different manners in which diatoms grow and
  live are definitely an sign of their diversity.
  Some diatoms grow by there self, while others may
  grow as a group or filaments that anchor them to
  surfaces. Some grows on another plant upon which
  it depends for mechanical support but not for
  nutrients , while others exist as parasites.
  Though some diatoms may be sessile, there are
  many that are free due to structures that allow
  movement. Those diatoms that do form colonies are
  usually liked by siliceous, mucilage, or
  polysaccharide structures.