Diatoms
By: Jared Williams
Andre Pierre-Louis
Chris Terrell
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.
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.
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).
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.
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.