Bacteria Shapes

Format
mla apa chicago
Your Citation
Bailey, Regina. "Bacteria Shapes." ThoughtCo, Feb. 5, 2017, thoughtco.com/bacteria-shapes-373278. Bailey, Regina. (2017, February 5). Bacteria Shapes. Retrieved from https://www.thoughtco.com/bacteria-shapes-373278 Bailey, Regina. "Bacteria Shapes." ThoughtCo. https://www.thoughtco.com/bacteria-shapes-373278 (accessed September 26, 2017).
01
of 06

Bacteria Shapes

Three basic shapes of bacteria
The three basic shapes of bacteria include cocci (blue), bacilli (green), and spiral (red - spirochetes). PASIEKA/Science Photo Library/Getty Images

Bacteria Shapes

Bacteria are single-celled, prokaryotic organisms. They are microscopic in size and lack membrane-bound organelles as do eukaryotic cells, such as animal cells and plant cells. Bacteria are able to live and thrive in various types of environments including extreme habitats such as hydrothermal vents, hot springs, and in your digestive tract. Most bacteria reproduce by binary fission. A single bacterium can replicate very quickly, producing large numbers of identical cells that form a colony. Not all bacteria look the same. Some are round, some are rod-shaped bacteria, and some have very unusual shapes. Bacteria can be classified according to three basic shapes: Coccus, Bacillus, and Spiral.

Common Shapes of Bacteria

  • Coccus - spherical or round
  • Bacillus - rod shaped
  • Spiral - curve, spiral, or twisted

Bacteria can also have different arrangements of cells.

Common Bacterial Cell Arrangements

  • Diplo - cells remain in pairs after dividing.
  • Strepto - cells remain in chains after dividing.
  • Tetrad - cells remain in groups of four and divide in two planes.
  • Sarcinae - cells remain in groups of eight and divide in three planes.
  • Staphylo - cells remain in clusters and divide in multiple planes.

Though these are the most common shapes and arrangements for bacteria, some bacteria have unusual and much less common forms. These bacteria have varying shapes and are said to be pleomorphic. Other unusual bacteria forms include star-shapes, club-shapes, cube-shapes, and filamentous branches.

 

  • Bacteria Shapes
  • Cocci Bacteria
  • Bacilli Bacteria
  • Spirilla Bacteria
  • Spirochete Bacteria
  • Vibrio Bacteria

02
of 06

Cocci Bacteria

Staphylococcus aureus bacteria
This antibiotic resistant strain of Staphylococcus aureus bacteria (yellow), commonly known as MRSA, is an example of cocci shaped bacteria. National Institutes of Health/Stocktrek Images/Getty Images

Cocci Bacteria

Coccus is one of the three primary shapes of bacteria. Coccus (cocci plural) bacteria are round, oval, or spherical in shape. These cells can exist in several different arrangements that include:

Cocci Cell Arrangements

  • Diplococci - cells remain in pairs after dividing.
  • Streptococci - cells remain in chains after dividing.
  • Tetrad - cells remain in groups of four and divide in two planes.
  • Sarcinae - cells remain in groups of eight and divide in three planes.
  • Staphylococci - cells remain in clusters and divide in multiple planes.

Staphylococcus aureus bacteria are cocci shaped bacteria. These bacteria are found on our skin and in our respiratory tract. While some strains are harmless, others such as methicillin-resistant Staphylococcus aureus (MRSA), can cause serious health issues. These bacteria have become resistant to certain antibiotics and can cause serious infections that may result in death. Other examples of coccus bacteria include Streptococcus pyogenes and Staphylococcus epidermidis.

  • Bacteria Shapes
  • Cocci Bacteria
  • Bacilli Bacteria
  • Spirilla Bacteria
  • Spirochetes Bacteria
  • Vibrio Bacteria

03
of 06

Bacilli Bacteria

e. coli
E. coli bacteria are a normal part of the intestinal flora in humans and other animals, where they aid digestion. They are examples of bacilli shaped bacteria. PASIEKA/Science Photo Library/Getty Images

Bacilli Bacteria

Bacillus is one of the three primary shapes of bacteria. Bacillus (bacilli plural) bacteria have rod-shaped cells. These cells can exist in several different arrangements that include:

Bacillus Cell Arrangements

  • Monobacillus - remains single rod-shaped cell after dividing.
  • Diplobacilli - cells remain in pairs after dividing.
  • Streptobacilli - cells remain in chains after dividing.
  • Palisades - cells in a chain are arranged side-by-side instead of end-to-end and are partially attached.
  • Coccobacillus - cells are short with a slight oval shape, resembling both coccus and bacillus bacteria.

Escherichia coli (E. coli) bacteria are bacillus shaped bacteria. Most strains of E. coli that reside within us are harmless and even provide beneficial functions, such as food digestion, nutrient absorption, and the production of vitamin K. Other strains, however, are pathogenic and can cause intestinal disease, urinary tract infections, and meningitis. More examples of bacillus bacteria include Bacillus anthracis, which cause anthrax and Bacillus cereus, which commonly cause food poisoning.

  • Bacteria Shapes
  • Cocci Bacteria
  • Bacilli Bacteria
  • Spirilla Bacteria
  • Spirochetes Bacteria
  • Vibrio Bacteria

04
of 06

Spirilla Bacteria

Spirilla Bacteria
Spirilla Bacteria. SCIEPRO/Science Photo Library/Getty Images

Spirilla Bacteria

Spiral shape is one of the three primary shapes of bacteria. Spiral bacteria are twisted and commonly occur in two forms: spirillum (spirilla plural) and spirochetes. These cells resemble long, twisted coils.

Spirilla

Spirilla bacteria are elongated, spiral-shaped, rigid cells. These cells may also have flagella, which are long protrusion used for movement, at each end of the cell. An example of a spirillum bacterium is Spirillum minus, which causes rat-bite fever.

  • Bacteria Shapes
  • Cocci Bacteria
  • Bacilli Bacteria
  • Spirilla Bacteria
  • Spirochetes Bacteria
  • Vibrio Bacteria

05
of 06

Spirochetes Bacteria

spirochete bacterium
This spirochete bacterium (Treponema pallidum) is spirally twisted in form, elongated and appearing thread-like (yellow). It causes syphilis in humans. PASIEKA/Science Photo Library/Getty Images

Spirochetes Bacteria

Spiral shape is one of the three primary shapes of bacteria. Spiral bacteria are twisted and commonly occur in two forms: spirillum (spirilla plural) and spirochetes. These cells resemble long, twisted coils.

Spirochetes

Spirochetes (also spelled spirochaete) bacteria are long, tightly coiled, spiral-shaped cells. They are more flexible than spirilla bacteria. Examples of spirochetes bacteria include Borrelia burgdorferi, which causes Lyme disease and Treponema pallidum, which causes syphilis.

  • Bacteria Shapes
  • Cocci Bacteria
  • Bacilli Bacteria
  • Spirilla Bacteria
  • Spirochetes Bacteria
  • Vibrio Bacteria

06
of 06

Vibrio Bacteria

vibrio cholerae bacteria
This is a group of vibrio cholerae bacteria which causes cholera. Science Picture Co/Getty Images

Vibrio Bacteria

Vibrio bacteria are similar in shape to spiral bacteria. Vibrio bacteria have a slight twist or curve and resemble the shape of a comma. They also have a flagellum, which is used for movement. A number of species of vibrio bacteria are pathogens and are associated with food poisoning. One example is Vibrio cholerae, which causes the disease cholera.

  • Bacteria Shapes
  • Cocci Bacteria
  • Bacilli Bacteria
  • Spirilla Bacteria
  • Spirochetes Bacteria
  • Vibrio Bacteria