Size, Shape, and Arrangement of Bacteria

In this size, shape, and arrangement of bacteria post we have briefly explained about bacteria, size, shape and different bacteria types of bacteria arrangement.

Shapes of Bacteria with Examples

“Bacteria are unicellular organisms belonging to the prokaryotic group where the organisms lack a few organelles and a true nucleus”. The structure of bacteria is known for its simple body design. Bacteria are single-celled microorganisms with the absence of the nucleus and other cell organelles; hence, they are classified as prokaryotic organisms.  Due to the presence of a rigid cell wall, bacteria maintain a definite shape, though they vary as shapes of bacteria with examples, size and structure.

Shapes of Bacteria with Examples: Size, Shape, and Arrangement of Bacteria

Most bacteria have one of three major morphologies when seen under a light microscope: the rod (bacillus), the sphere (coccus), or the spiral variety (vibrio). Bacterial structure is divided into two parts: organisation and form.

It can be paired (diplo), grape-like clusters (staphylo), or chains in terms of arrangement (strepto). Rods (bacilli), Spheres (cocci), and Spirals are the most common shapes (spirillum).


In general, bacteria are between 0.2 and 2.0 um – the average size of most bacteria. E.coli bacteria range between 1.1 and 1.5 um in diameters, B.anthracis range between 1.0 and 1.2um while B.subtilis range between 0.25 and 1.0um in diameter.

Shapes of Bacteria with Examples

Schaudinnum bütschlii that measure between 4 and 5um in diameter are considered to be large bacteria, Thiomargarita namibiensis may grow to be as large as 0.75mm in diameter.

Mycoplasmas (about 0.25um), Haemophilus influenzae which ranges between 0.2 and 0.3um and Mycoplasma gallicepticum which range between 200 and 300 nanometers in diameter.


Bacteria are microscopic single-celled creatures that lack membrane bound organelles and are small in size. A cell wall and capsule protect the inner contents of the cell, which include the nucleoid, ribosome, plasmid, and cytoplasm, in the majority of these species.

While the majority of bacteria have these features, their shapes varies, allowing bacteria to be classed based on their basic shapes of bacteria with examples.

Cocci: Cocci bacteria have a spherical or oval form. The form is mostly influenced by the organism’s cell wall and so differs from one species of cocci bacterium to the next. Cocci bacteria can exist as solitary cells or as groups of cells that remain linked to one another.

Bacillus: Bacillus bacteria, like cocci bacteria, are structured differently. Others, such as Salmonella enterica subsp., Bacillus cereus, and Salmonella choleraesuis, exist as solitary, unattached cells.

Spirilla: Spirilla (or spirillum for a single cell) are curved bacteria that can range in shape from mildly curled to a corkscrew-like spiral. Many spirilla are both rigid and mobile. Spirochetes are a bacteria types of spirilla that is long, slender, and flexible.


Bacterial Cells

Shapes of Bacteria with Examples

Diplococci Bacteria: Diplococci bacteria are cocci bacteria that occur in pairs (two joined cells). While some of these cells are really round, others are elongated (ovoid) or bean-shaped/kidney shaped. When seen under a microscope, certain Neisseria cells may appear round, while others may appear bean-shaped.

Tetrad Bacteria: Tetrad bacteria are bacteria that are grouped in four-cell clusters. The cells remain attached after division and proliferate in this connection.

Sarcinae Bacteria: Sarcina bacteria are found in eight-cell clusters. Unlike tetrads, which divide into two planes, Sarcinae is formed by dividing the planes perpendicularly. These bacteria have a number of traits, including being stringent anaerobes, Gram-positive bacteria, and measuring between 1.5 and 3.0 um in diameter.

Streptococci Bacteria: Streptococci bacteria are a type of bacteria that cluster together to create a chain. The bulk of these bacteria has an oval shape and can form paired chains. This group of bacteria, which belongs to the Streptococcaceae family, is known for being Gram-positive and non-motile.

Staphylococci Bacteria: Bacteria Staphylococci are a sort of bacteria that produce clusters that look like grapes. This type of layout is the outcome of two-plane division. The fact that these organisms are Gram-positive bacteria and that they are stationary are two of their most distinguishing properties.


Shapes of Bacteria with Examples

Diplobacilli Bacteria: Diplobacilli bacteria are found in pairs. The two cells do not split after cell division and continue to live as a pair.

Streptobacilli Bacteria: Streptobacilli bacteria are found in the form of elongated chains. As a result, they are the outcome of a single-plane division.

Coccibacilli Bacteria:  Coccibacilli bacteria are shorter than other bacilli, making them appear stumpy.

Palisades Bacteria: These bacteria form a picket fence-like configuration as a result of cell division. The Corynebacterium diphtheria, which causes diphtheria, is one of the best examples of palisades.


Bacterial Cells

Shapes of Bacteria with Examples

Vibrio Bacteria: These are gram-negative bacteria that are comma-shaped and not totally bent or twisted. They’ve been linked to foodborne infections and disorders. The microorganism has the shape of a comma. Vibrio cholera, the causative agent of Cholera, is a common example of this species.

Spirilla Bacteria: This type of bacteria is a gram-negative, flagellated genus of spiral-shaped bacteria. Spirillum minus is a spirilla bacteria that has been linked to rat-bite fever. Aquaspirillum and Oceanospirillum are examples of free-living aquatic bacteria in this genus.

Spirochete Bacteria: Spirochete bacteria are arranged in a spiral that mimics lengthy helically coiled cells. They are pathogenic and have been linked to major human illnesses. Treponema pallidum, which causes syphilis, is an example of this class of bacteria. In humans, the borellia species causes Lyme disease.

Others Shapes

Rectangular: A rectangular-shaped bacteria, commonly known as an arcula, is the first unusual shape bacteria. Haloarcula vallismortis and Haloarcula marismortui are two bacterial species in this genus. They grow at temperatures between 40 and 45ºC and are exceedingly halophilic. They aren’t pathogenic and haven’t been linked to any illnesses.

Appendage Cells: A heterogeneous group of microorganisms or bacteria known as appendage or budding bacteria. They have a different way of reproduction than other bacteria. They may or may not be mobile. The motile species, on the other hand, are frequently flagellated.

Pleomorphic Cells: Under the stress of environmental variables, this word alludes to the ability to shift or alter size and shape. Mycoplasma pneumonia, for example, is the causal agent causing pneumonia.

Star shaped Cells: A star-shaped bacterium is a bacterium with an odd shape that resembles a flat, six-pronged star. Stella, for example, is a species that can be found in freshwater, soil, and sewage.

Pleomorphic Cells: Unlike the other microorganisms discussed above, these bacteria do not have a distinct shape. They have the ability to modify their shape. They can be seen in a variety of shapes in pure cultures.

Further Readings


shapes of bacteria with examples