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Arrangement of cocci bacteria.svg
Staphylococcus bacteria

Coccus (plural cocci or coccuses) can be used to describe any bacterium that has a spherical shape. It is one of the three distinct types of bacteria shapes, the other two being bacillus (rod-shaped) and spirillum (spiral-shaped) cells. Coccus is an English loanword of a Neolatin noun, which in turn stems from the Greek masculine noun kokkos (κόκκος) meaning "berry".[1]

The term 'coccus' is used in botany to denote a mericarp or 1-seeded segment of a schizocarp.


Like all bacteria, each single coccus bacterium is an entire living organism. And some species exist in groups of cells. If they do group together,[2] the patterns they arrange themselves in are given certain names based on the shape. Diplococci are arranged in two-cell pairs; these may represent several different genera. Bacteria in the Streptococcus genus are arranged in chains. Bacteria in the Sarcina genus typically form a cuboidal arrangement of eight cells. Staphylococcus is a genus of bacteria characterized by cells arranged in tetrad clusters (four cells in a square formation) or large, often irregular, grape-like clusters. While groups of cells together form these characteristic shapes, the individual bacterial cells themselves will appear as distinct circles within the chain or cluster.


  1. ^ κόκκος. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
  2. ^ Councilman, William Thomas. Disease and Its Causes. Project Gutenberg. Retrieved 27 March 2010.