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Bacteria Shapes

Bacteria are single-celled organism. They don’t have nucleus or membrane organelles, although some have plasmid, an extra circle of genetic material.

It gives bacteria a greater advantage over other bacteria such as resistance to particular type of antibiotic. They are microscopic in size and can live and thrive in different types of environments. They are found in various parts of the earth such as soil, ocean, rock, artic snow, plants, animals, and even in the human body.

The number of bacteria is ten times more than the cells in the human body. A lot of bacteria can reproduce by binary fission and a single bacterium can replicate rapidly. (1, 2, 3)

Bacteria vary in size and shape. Some are round while others are rod-shaped. In fact, some bacteria have unusual shapes. The three main shapes of bacteria are coccus (spherical). Bacillus (rod), and spirilla (spiral). Less common shapes are spirochaetes (corkscrew) and vibrios (comma).

The shapes are subdivided according to the arrangement of bacteria. (2)

A photo showing the three common shapes of bacteria picture

Picture 1: A photo showing the three common shapes of bacteria
Photo Source: monag9a.files.wordpress.com


Shapes and arrangement of bacteria.photo

Image 2: Shapes and arrangement of bacteria
Picture Source: www.kullabs.com

Bacteria Shapes chart images pictures


Picture 3: The basic morphology of bacteria

What are the three main arrangements of bacteria?

The common arrangements of bacteria are diplo (the cells remain in pair after division), strepto (cells remain in chains after division), and staphylo (cells remain in cluster and then eventually divide into various planes.) less common bacterial arrangements are tetrad (cells in group of four divide in two planes) and sarcinae (group of eight and eventually divide in three planes).

Some bacteria have unusual forms. They are called pleomorphic. (4, 5)

Typical shapes and arrangements of bacteria

Cocci bacteria

Their shapes are round, oval, and spherical. They are commonly known as spherical shaped bacteria. The cells of cocci bacteria can be arranged in diplo, strepto, tetrad, sarcinae, and staphylococci. A perfect example of cocci shaped bacteria is Staphylococcus aureus.

They are typically found on the skin and in the respiratory tract. Some of them are harmless while others can be very harmful to your health. An example of harmful cocci bacteria is methicillin-resistant Staphylococcus aureus (MRSA. It is resistant to certain types of antibiotics. If the infection is severe, the person could die. Other examples of cocci bacteria are Staphylococcus epidermidis and Streptococcus pyogenes.(6)

Bacilli bacteria

It is a rod shaped bacteria and is one of the common bacterial shapes. Their typical arrangements are monobacillus, diplobacilli, streptobacilli, and palisades. What is meant by a palisade arrangement of cells? It means that the cell of bacteria is arranged side by side instead of end to end. The cells are partially attached too. An example of a bacillus shaped bacteria is Escherichia coli or E. coli.

They are typically harmless and reside in the human body. In fact, some of them helps in the normal functioning of the body such as aiding in food digestion, absorption of nutrients, and production of vitamin K. Some strains are harmful as they can cause urinary tract infection (UTI), intestinal diseases, and meningitis. Other rod shaped bacteria examples are Bacillus cereus (causes food poisoning) and Bacillus anthracis (causes anthrax).

There is another bacterial shape called coccobacillus. They resemble both of the coccus and bacillus bacteria. They are short and slightly oval in shape. (2, 8)

Spirilla bacteria

These bacteria are spirilla shape. They are twisted and occur in two forms: spirilla and spirochetes. They look like long, twisted coils. Their cells are elongated and rigid. They can have flagella, a long protrusion that aids in the movement of bacteria. A perfect example of spirillum bacteria is Spirillum minus (responsible for causing rat-bite fever). (9)

Spirochetes bacteria

These are spiral shaped bacteria. They are twisted and occur in two forms: spirochetes and spirillum. Their cells are long, spiral in shape, and tightly coiled. They look like spirilla bacteria, but spirochetes are more flexible. Examples of spirochetes shaped bacteria are Treponema pallidum (causes syphilis) and Borrelia burgdorferi (causes Lyme disease). (1, 10)

Vibrio bacteria

They are somewhat similar to that of the spiral shaped bacteria. However, vibrio bacteria are comma shaped bacteria. They have slightly twist or curved cells. They too have flagellum, which aids in their movement. Most of these bacteria cause disease and they are mostly associated with food poisoning. An example of vibrio bacteria is Vibrio cholera, which causes cholera. (4)

How do bacteria reproduce?

They reproduce through the process called binary fission. It pertains to the division of single cell into two identical daughter cells. The binary fission process starts when the DNA of bacteria splits into two. It will then elongate and will eventually split into daughter cells.

The DNA of the daughter cells are the same to that of the parent cell. In other words, the DNA of daughter cells is clone of the parent cell. Some bacteria can divide rapidly, especially during favorable environment condition such as the right temperature and nutrients. For example, the E. coli can divide every 20 minutes. In just a few hours, one bacterium can multiply into thousands, if not millions of bacteria. As the number of harmful bacteria increases, the more the human body become ill. (6, 7, 8)

Why some bacteria are resistant to antibiotics?

Bacteria have survival mechanisms. Some of them have the ability to form endospores, which make them resistant to physical and chemical conditions such as radiation, ultraviolet rays, and disinfectants. The ability of the bacteria to form endospores makes it extremely difficult to destroy them.

A perfect example of endospore-producing bacteria is Bacillus anthracis, which causes anthrax. (10)

How to get rid of harmful bacteria?

  1. Boiling water – Bacteria in drinking water can make you ill. To eliminate the bacteria in water, you have to boil it for a few minutes.
  2. Structured silver – It can eliminate bacteria in and on the body. It can kill drug-resistant bacteria but does not affect the good bacteria (probiotic).
  3. Chlorination – A chlorine is added to the water to get rid of bacteria.
  4. Prescription medicines – Antibiotics are effective in destroying disease-causing bacteria.

There are other ways to get rid of harmful pathogens. The treatment approach depends on the type and nature of bacteria. (6, 8, 9)


  1. www.quora.com
  2. www.thoughtco.com
  3. www.microbiologyinfo.com
  4. microbiologyonline.org
  5. https://en.wikipedia.org
  6. www.brighthub.com
  7. www.sciencelearn.org.nz
  8. www.ncbi.nlm.nih.gov
  9. www.shutterstock.com
  10. Germs, Genes, and Bacteria: How They Influence Modern Life (Collection) By David Clark, Greg Gibson, Anne Maczulak

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