Vorticella are the eukaryotic ciliates that belong to the protozoa. These organisms are considered to be the largest genus of sessile peritrich ciliates, they belong to the phylum of Ciliophora. They are generally found in a humid climate, they are found in ponds, salty lakes and they can also be found in freshwater sources. Vorticella under microscope has a characteristic feature of beating cilia creating whirlpools, or vortices. This is the reason that has been attributed to the name vorticella. Vorticella protozoa have a bell-shaped structure, due to which they are also named as “Bell Animalcule”. They were first discovered by Anton van Leeuwenhoek, he described the organism as having horn-like vorticella stalks which were later found to be cilial appendages.
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Vorticella classification has been performed according to the taxonomic classification rules, the taxonomic classification of vorticella can be summarized as,
This class of organisms is classified as the largest group of sessile protozoans there are some examples of species under vorticella classification, they are as follows,
These species are important parts of the food chain and play vital roles in the ecosystem that is important for humans.
Vorticella are found in aquatic systems, they are found in freshwater water bodies such as ponds and lates. They usually live in solitary, they are sedentary, which refers to the attachment of the organism to a rigid surface. They are attached to weeds, leaves, and other aquatic vegetation through their stalk, which provides the site of attachment. Even though they live in groups they are free-living independent. They are found in abundance in stagnant water rich with organic matter. It is that vorticella preys on the bacteria that grows on the stagnant organic decaying water. Vorticella protozoa are not only confined to freshwater but are also found in marine or salty water bodies.
Vorticella structure is quite unique, they are known for their bell-shaped bodies. Vorticella campanula is the largest species of vorticella, they have a characteristic feature of the asymmetrical inverted bell-like body. They also possess a stalk that helps in the attachment of the organism to the rigid structure providing the support for growth. The intricate details of the bell of vorticella structure are explained below,
Peristome- It is the peristomial collar of the bell, it is also known as the lip of the bell. It is thickened at the margins or borders around the rim. It has shallow depression inside it which is known as the peristomal groove or oral groove. They are fused around the oral disc to form the closing of the structure.
Vestibule- This is the permanently open sunken space between the peristome and the peristomial disc at the left is known as the vestibule. These are commonly known as infundibulum tubes. cytopharynx originates from it leading to the endo cytoplasm, it lacks any cilia.
Cilia - These are the appendages that arise from the membrane, they have primarily involved in vorticella movement and food capture. The body and the stalk do not have cilia but they do have the presence of a kinetosome, which lines the body. During the process of feeding, the cilia capture the food particle which is passed down through the cilia lining, the food particle moves down by the undulations of the inner row of cilia.
Pellicle- It is a thick covering that surrounds the complete bell structure, they also help in stalk attachment.
Stalk- These are the appendages that attach the organism to the surface, they are the extension of the pellicle, but it is covered by an additional layer known as the external cuticle, the stalk senses stimulus like change in environment, touch. etc. When such a condition appears the stalks coil themselves into a spiral form, the body rounder and the peristome goes into the closed conformation.
Cytoplasm- The cytoplasm contains all the cellular enzymes and organelles responsible for the survival of the organism. It can be divided into ecto and endo cytoplasm.
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Vorticella movement is also referred to as the locomotion of the vorticella. Vorticella under microscope has shown locomotion which is mediated by the cilia. Vorticella microscope structures are generally bound to the surface but when the stalk breaks for some reason the bell detaches from the stalk it floats freely with the help of cilia. Such free-flowing vorticella is known as the telotrochs. The attached vorticella move while remaining bound to the substrate, they swim around the axis provided by the stalk. Location is important to ensure the capturing of the bacteria, which are later phagocytosed by the vorticella protozoa.
Reproduction in Vorticella
Vorticella can undergo both sexual reproduction and asexual reproduction. Like simpler organisms, vorticella undergo asexual reproduction by the method of binary fission.
Binary fission is the method of reproduction where the cellular components double and then divide, giving rise to two daughter cells. Binary fission in vorticella starts with the shortening of the vorticella body, which occurs as the result of an increase in the width of the body because of an increase in the cellular component of the body. It is followed by the division of the nucleus. It is important to note the after fission the original parent vorticella retains its stalk. The daughter cell may generate its stalk, before the stalk generation the vorticella has cilia in place of the stalk.
Vorticella uses the sexual reproduction method, like conjugation and fusion.
Survival in Harsh Conditions
They survive harsh living conditions by detaching from the parental vorticella. They detach from the substrate and swim, this is followed by the coiling of the peristome into a more rounded structure. They also undergo encapsulation. It is a process in which a gelatinous covering is secreted which solidifies around the organism and forms a capsule. Encapsulation is done to protect the protozoa from predators and harsh conditions. It reproduces and attaches itself to the substrate when favorable conditions are found.
Importance of Vorticella
They feed on the smaller protozoa and bacterias that help in maintaining the population of the species, thus proving very important in the food web. They are also important because of their role in sewage treatment, they break down the organic matter found in the sewage plants and wastewater.