What shape are spherical bacteria called?

Spherical bacteria are called cocci. The term is the plural of coccus, a word derived from the Greek kokkos, meaning “berry,” and it describes a bacterium’s overall shape rather than a single taxonomic group or species.

Cocci may occur as individual cells or in recognizable arrangements created by the direction and timing of cell division. Staphylococci form grape-like clusters, streptococci form chains, and some species appear in pairs called diplococci. Sarcina bacteria can form regular packets of eight or more cells.

Cocci are often contrasted with bacilli, which are rod-shaped, and spirilla, which have spiral forms. Vibrio describes curved, comma-shaped bacteria rather than spherical ones. Shape alone does not identify every bacterium: cocci can differ in cell wall structure, metabolism, genetics, and disease-causing ability. Important human pathogens with coccoid forms include Staphylococcus, Streptococcus, and Neisseria.