Whether or not you have heard of Vorticella before, there is a high likelihood that you have benefitted from them in an indirect manner.
These protozoa organisms play a huge role in the maintenance of the aquatic ecosystems that they inhabit. In this article, we will look at the characteristics, structure, reproduction, and habitat of Vorticella.
What Is Vorticella?
Before we begin to discuss the specifics of Vorticella in detail, let’s cover the basics, namely, what is Vorticella?
Vorticella is a protozoan, or unicellular organism, that belongs to the Phylum Ciliophora.
As they belong to this specific Phylum, they are eukaryotic ciliates that are most commonly found within aquatic environments such as freshwater and marine environments, among others.
Vorticella are often found in large groups and have over 150 identified species within the genus. These organisms feed on the various food sources that naturally occur in their environment with the help of their vestibule.
Vorticella belongs to the food chain, however, they also play a very important role in our surroundings which helps the quality of life experienced by mankind.
Vorticella, when viewed under the microscope, has a unique characteristic of beating cilia which are adept at creating whirlpools, or vortices.
This is the reason behind their apt name, Vorticella. Vorticella protozoa present a bell-shaped structure, due to their striking look, they are also known as “Bell Animalcule” by some.
Some of the species present within the genus include:
- Vorticella Marina
- Vorticella Communis
- Vorticella Striata
- Vorticella Utriculus
- Vorticella Sphaerica
- Vorticella Campanula
- Vorticella Citrina
The classification of Vorticella protozoa has been established in line with the taxonomic classification rules. The classification of Vorticella protozoa can be classified under the following:
- Kingdom- Chromalveolata
- Phylum- Ciliophora
- Superphylum- Alveolata
- Class- Oligohymenophorea
- Subclass- Peritrichia
- Order- Sessilida
- Family- Vorticellidae
Reproduction And Lifecycle
There are multiple ways in which Vorticella protozoa are able to reproduce. Below we will explore the three main methods of reproduction in these organisms.
As with many other tiny aquatic organisms, Vorticella often reproduces asexually, most commonly via a process of fission. During this process, Vorticella protozoa will divide into two or more daughter cells in order to form new Vorticella organisms.
Prior to the act of splitting into daughter cells, the Vorticella undergoes some physical changes in preparation for the process.
The organism shortens its body as it becomes wider as if it were being squashed under an invisible weight if you were viewing it.
Following this alteration in physical appearance, the nucleus undergoes a process of division to prepare for the formation of a new Vorticella.
During the splitting of the nucleus, the macronucleus will divide amitotically while the micronucleus will divide mitotically.
As the division process occurs the constriction that is required begins at the cell wall, this gradually divides the cell lengthways. Finally, a division of the organism into two separate, unequal organisms is complete.
In the instance that a parent Vorticella divides into two or more new organisms, only one of the resulting organisms will contain the original stalk.
In the other newly formed organisms, new cilia, or temporary cilia, will need to be developed. This will form the stalk that will allow the organism to attach to another surface or substrate.
The unequal and longitudinal nature of the fission exhibited in Vorticella is widely considered to be unique in comparison to other ciliates.
The process of fission in Vorticella takes between 20 and 30 minutes to complete and happens as follows.
As the fission process begins, the opening of the vestibule begins to close up as the body of the Vorticella begins to shorten and increase in width.
This is known as transverse elongation. The contractible wall pulsates during the process of division while the macronucleus begins to shorten and condense as it relocates itself within the cell.
As the process continues to unfold, constriction increases at the anterior end of the cell which will gradually divide the cell vertically.
This begins at the tip of the vestibule and continues down towards the stalk. Once this process is completed, the cell has been divided into two parts, with one of the daughter cells being of a smaller size.
The larger, parent cell retains the stalk with which it remains attached to its original surface.
The smaller, daughter cell lacks a stalk but is able to develop cilia at its posterior. In comparison to the parent cell, the smaller cell is more cylindrical in shape, this is known as a telotroch.
Using the newly developed cilia, the cell is able to swim away and attach to a new surface through its scopula (a small brush-like structure).
The scopula is also used to produce a new stalk for the daughter cell that will allow the organism to remain attached to its new surface. Over time, the cylindrical shape will develop into the unique bell shape that the Vorticella is known for.
While Asexual binary fission is the most common means of reproduction among Vorticella, they have also been known to reproduce through conjugation or sexual reproduction.
There are two main stages involved in the conjugation of Vorticella that we will outline below.
Formation Of Micro And Macro-Conjugants
This phase involves the same binary fission process that produces a larger and smaller cell as described above. Here, the smaller cell which, in some cases, may be more than one, is labelled as the micro-conjugant.
The next step for the micro-conjugants that are created in this phase is to develop posterior cilia, as mentioned above. As this newly formed cell has detached from the larger parent cell, it will swim and attach to another surface.
Compared to the telotrochs that are produced through asexual reproduction processes, micro-conjugants are usually smaller in size.
Additionally, micro-conjugants do not end up metamorphosing into a fully developed adult form nor do they develop a stalk. Within 24 hours, they will die off rather than enclose as some forms of telotrochs might do when facing tough conditions.
The larger cells that have retained the stalk proceed to undergo nuclear modifications, ultimately developing into what is known as macro-conjugants. Once they are in this state, the macro-conjugant can sexually reproduce with a viable micro-conjugant.
Once the Vorticella has successfully undergone binary fission to create micro and macro-conjugants, the second stage of sexual reproduction can commence. This stage is commonly referred to as Fusion.
While the micro-conjugants swim through the water using their posterior cilia, they can encounter the macro-conjugants.
When these encounters occur, the micro-conjugant will attach themselves to the lower part of the macro-conjugants cell body in a location near to the stalk.
Once successful attachment has occurred, the cilia will fall off and changes to the nucleus in both conjugants will begin to happen.
Within both conjugants, the macronucleus will break down and be absorbed into the cytoplasm present in the cell.
The micronucleus present in both conjugants then proceed to divide and result in four micronuclei in the macro-conjugant, and eight micronuclei in the micro-conjugant.
Once all of the micronuclei have been formed, all but one in each conjugant will degenerate, leaving a single female pronucleus in the macro-conjugant and a single male pronucleus in the micro-conjugant.
Once the correct pronuclei have been formed, the cell wall between the conjugants breaks down to facilitate the fusion of the pronuclei which results in the formation of a Zygote nucleus.
The Zygote nucleus proceeds to divide further, producing seven macronuclei and a singular micronucleus which then splits further into two micronuclei that will be separated once the cell has divided fully.
The end result of this complex process is the existence of one cell with a single micronucleus and four macronuclei and another with three macronuclei and a single micronucleus.
This process of division continues until cells with singular macro and micronuclei are formed.
The final result of the fusion is seven daughter cells that will develop stalks over time and once they reach full maturity they will be able to continue the lifecycle and reproductive process.
Survival Of Vorticella
There are some scenarios when the surrounding conditions that Vorticella end up in prove unfavorable, there have been some studies.
Showing how the organisms will detach from the substrate that they have anchored to and swim freely to surroundings with more favorable conditions.
However, when a Vorticella finds itself in extremely unfavorable conditions or conditions that are posing a threat to their survival, a cyst is formed for protection.
The process of forming the cyst begins with the withdrawing of the vestibule opening. The organism will then begin contracting into a spherical shape.
A gelatinous covering will then be secreted by the organism that will ultimately solidify and form a protective capsule. The protective capsule shields the organism for the duration of the extreme environmental conditions.
This is a process that works when the unfavorable conditions have been created by temporary pollutants.
Within the protective cyst, the nucleus and contractile vacuole of the organisms may remain unchanged, however, it is possible for the nucleus to break down into several tiny, disc-shaped fragments during the period of encapsulation.
When conditions improve it is normal for the cyst to break open to release the organism. Upon release into the favorable surrounding, a space within the cell’s cytoplasm will develop and start pulsating.
As the organism begins to enlarge once more, a circular band of cilia is produced at the posterior end which will form a telotroch.
The vorticella will then proceed to swim freely until it encounters a substrate or surface to attach to, when this occurs a stalk will eventually develop as the organism reaches full maturity.
Structure And Characteristics
It is possible for students and scientists to easily observe the different parts, characteristics, and structures of Vorticella using a phase contrast microscope.
One of the biggest benefits of using this type of microscope to study Vorticella is that it is designed to alter the speed of the light entering the more dense areas of the organism.
This then causes certain parts of the organism’s structure to appear more clearly in comparison to the less dense areas, allowing for a more intricate analysis of their structure.
The most important aspect of this technique is that it allows for the observation of living organisms, which in turn makes it possible to view and understand the organisms while they are still alive.
This allows us to understand the way they would behave in their natural habitat.
The procedure for observing the living Vorticella simply involves the procuring of the organism from any water body in which the Vorticella organism may be found and placing it under the phase contrast microscope.
One of the more distinct characteristics that are visible when observing the Vorticella is the cone or bell-shaped body that separates it from almost any other protozoan.
It is possible for scientists and students to see fine hair-like structures that are present on the upper part of the bell shaped vestibule of the organism.
These fine hair-like structures are commonly called cilia and they play the vital role of sweeping food material into the wide mouth-like opening surrounded by cilia.
There is also a slender stalk at the base of the organism’s body. This stalk plays the important role of attaching or fixing the organism to a substrate or other surface that then allows the Vorticella to float and feed on passing organic material within the water.
It is the presence of this unbranched stalk that successfully distinguishes Vorticella protozoa from the other ciliate species.
Another one of the Vorticella’s more unique characteristics is that the distinctive stalk contains a substance called myoneme which is a contractile thin fiber that makes it possible for the stalk to be shortened and to coil when it is stimulated.
This means that, when the organism is being observed under the microscope, it is possible to witness the stalk coiled up like a spring. This is a direct result of the stimulation caused by the handling of the Vorticella.
Vorticella are organisms that are considered to be suspension feeders. This means that they will feed on organic matter that swims past them, these can include other smaller protozoa, tiny organic material, and even bacteria.
However, it is important to note that for the most part, the telotroch form of the organisms are actually non-feeders.
When the Vorticella are in favorable conditions they will start to reabsorb the somatic cilia which then provides the organism with the energy and the material required for the stalk to be secreted and for the process of metamorphosis.
Once the Vorticella has matured and formed a stalk, they will attach themselves to a substrate or other surface and begin to feed on a range of material in their surroundings.
The Vestibule houses the opening through which food material is consumed. Around the entrance of this mouth-like opening are tiny cilia that have an important role to play in the sweeping of food material from the surrounding waters into the oral groove to be consumed.
Vorticella will feed on the many bacteria that grows on the decaying organic matter within stagnant waters.
The size of a Vorticella varies depending on the specific species of the organism. For the Vorticella campanula, the unique bell shaped body has been recorded as measuring at a length of around 157 microns and a width of around 99 microns.
The stalk that vorticella have on the other hand has been shown to vary considerably, measuring in length anywhere from around 53 microns to as long as 4150 microns.
Vorticella protozoa are most commonly located in fresh bodies of water such as ponds, lakes, rivers and streams. However, it is also possible for them to be located in salty environments, such as marine waters, as well as within some aquatic vegetation.
Even though Vorticella are often found in groups they are actually free-living and independent. They can be found in abundant numbers in stagnant waters that are rich with nutritious organic matter.
The specific environments that Vorticella are found in are ideal primarily because they provide ideal sources of food. As mentioned in the above sections, Vorticella commonly attach themselves to substrates or other surfaces via their stalk.
Because of this, they are not generally known to swim freely in search of food. However, within their aquatic habitats, it is easy to acquire food from their immediate surroundings in the water.
Importance Of Vorticella
Within their specific environments, Vorticella protozoa play an important role in the preservation and health of the delicate ecosystems. Their ability to feed on smaller protozoans and bacteria make them perfect for exercising population control within the waters.
They are also an organism that is rife within sewage treatment systems and aquatic farm ponds. The vorticella are useful in such systems due to their ability to consume and break down the organic matter that may be present.
This allows them to effectively clean the water and maintain the quality of the water.
Vorticella are incredible organisms that provide a lot of value to the environments that they inhabit. They also have the incredible ability to protect themselves from adverse conditions and reproduce in intricate and complex manners.
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