What are Microorganisms?
Different Types found in Pond Water etc
Microorganisms are simple,
single celled organisms that can be found all around the world. They are largely
composed of the members of the plant kingdom, fungi, bacteria and protozoa. As
such, they are only visible under the microscope.
However, as is the case with
some species, microorganisms may cluster together in large numbers (colonies),
which allows them to be visible to the naked eye or when using a magnifying
glass.
Typically, pond water will
contain a variety of microorganisms with a drop of the water carrying thousands
of these single celled organisms.
Some of the most common living
in pond water include:
Pond water contains a
number of arthropods such as copepods, water fleas and ostracods (crustaceans).
These types of microorganisms are visible to the naked eye (with the largest
specimen exceeding 3 millimeters in length), and can therefore be seen without
the use of a microscope.
Some of the other organisms in this group include
among others; water mites, mosquito larvae, water bears (tardigrades) water
shrimp and other larger crustaceans like the water louse.
Depending on the type
of arthropod, some will be found on the surface (most insects) while others can
only survive in the water as is the case with most crustaceans.
Bacteria are some of the
smallest and abundant microorganisms in all aquatic systems. In favorable
conditions (E.g. after rainfall) bacteria can multiply and increase
dramatically to their millions (millions per milliliter) within a short period
of time.
In pond water, bacteria can be found on the surface of different types
of decaying material such as leaves, metallic objects, rocks or wood. This is
one of the reasons an individual may get a serious infection after being
scratched by such objects.
There
are different types of bacteria that can be found in a pond including
autotrophic and heterotrophic bacteria. Whereas autotrophic often categorized
as algae (bring primary producers) heterotrophic bacteria play a major role in
the decomposition of organic matter. While heterotrophic bacteria are often
categorized as "algae" it is important to note that they are not
closely related to algae.
These not
only make up the larger percentage of living organisms in such aquatic systems,
but also tend to display the greatest range of metabolic group as compared to
others. Nostac and anabaena are some of the most common bacteria
that can be found in pond water. Being cyanobacteria, they are
also responsible for the greenish coloration of pond water.
Being animal like, protozoan
are very similar to simple animals. These microorganisms make up the largest
group of organisms in terms or numbers, diversity as well as biomass. As such,
protozoa widely vary in terms shape, size and features.
Protozoa are also an
example of microorganisms that may form clusters (colonies). Like bacteria,
there are autotrophic and heterotrophic bacteria. Unlike bacteria however,
these also tend to consume a variety of other organisms;
including algae and other protists.
With the other
microorganisms found in pond water, protozoa makes up the bio-film that coats
sediments as well as other had surfaces. Their ability to move makes it
possible for them to move from one place to another without heavily relying on
water movement.
As such, they can move around consuming other organisms.
Some of the most common protozoa that can be found in pond water include
amoebas, paramecium and a number of ciliates.
Hydra belongs to the class hydrozoa,
most members of which can be found in marine water. However, hydras are mostly
found in pond water and tend to be predatory animals, which hunt their prey.
A
majority of these microorganisms tend to be small, only growing to be about 30
mm long when they are fully extended. To the naked eyes, hydra can barely be
seen, and therefore at least a hand lens would be required to get a good look
at them.
There are different types
of hydra with colors ranging from green to brown. The green color of some of
these microorganisms is as a result of green algae, with which they have a
mutually beneficial relationship. It is as a result of this relationship that
some students may mistake hydras as belonging to the plant kingdom.
Although they will mostly be found attached to a given surface, they can detach
and move from one spot to another either by gliding along the surface or simply
by "somersaulting" along the surface they are attached to
(substratum).
Algae are autotrophic
protists that can be found in pond water. Most of these microorganisms are
green in color, while a few may be yellowish-brown. Algae are also diverse, and
may either be unicellular or multicellular.
Some of the most common forms of
algae that may be found in pond water include spongomonas, euglena as well as
chlamydomonas. While some of these microorganisms (chlamydomonas) swim freely
in search of food, others (spongomonas) live in gelatinous matrices and use
special features to collect food without moving from one point to another.
Based on their
characteristics, algae may be categorized as:
- Planktonic
algae - Algae that floats on the surface of pond water
- Filamentous
Algae- also referred to as pond scum, this type of algae rise to the
surface of the water from the bottom
- Colonial
Diatoms - Tends to grow in colonies
- Resistant
algae - they have special features and characteristics that allow them
to remain resistant and therefore hard to control
- Toxic
Algae - Blue-green bloom forming species of algae
Conclusion
Pond water is also fresh
water. For this reason, the two terms may be used interchangeably when talk
about the types of microorganisms found in pond water.
On the other hand, given
that there are a variety of microorganisms that can found in ponds, it is also
important to keep in mind that not all microorganisms are protists. This is
because of the fact that the term is only used to refer to the group of diverse
eukaryotic, which may share certain traits with animal and plants.
For this
reason, most bacteria cannot be described as protists because their traits and
structures differentiate them from members of the protist group.
Related: Unicellular Organisms and Multicellular Organisms
Take a look at our page on Coliforms and Fungi.
Learn about Serotype and Antigens
Return from Microorganisms to Pond Water Under the Microscope
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