Rod-shaped bacteria curved to form commas are known as:

• A. Spiral
• B. Cocci
• C. Bacilli
• D. Vibrios

Answer: (D)

In bacterial shapes, how a cell looks in form matters for naming. Rod-shaped bacteria that are straight are called bacilli, while those that are spherical are cocci, and those that form a spiral are spirilla or spirochetes. When a rod bends into a curved, comma-like form, that shape is described as a vibrio. This curved-rod appearance is the defining feature that sets vibrios apart from straight bacilli or round cocci, and from the helical spirilla/spirochetes. An example you may have heard of is Vibrio cholerae, named for its curved rod shape. So, the comma-shaped, curved rod best matches the description of vibrios.