What are the shapes of bacteria?

Bacteria are classified based on their shapes, which are primarily categorized into three distinctive forms: spherical, rod, and spiral. The spherical shape is referred to as cocci, the rod shape is known as bacilli, and the spiral shape is termed spirilla or spirochetes. These shapes are fundamental in microbiology for identifying and classifying bacteria, as they can influence the behavior and characteristics of the bacteria, including how they interact with their environments and how they respond to antibiotics.

The other options present shapes that do not accurately reflect the primary classifications of bacteria. For instance, triangular and square shapes are not seen in bacterial morphology, as bacteria do not typically exhibit such geometric forms. Similarly, shapes such as cubic, filamentous, and oval do not align with the established bacterial classifications. Understanding these basic shapes is critical as it serves not only for identification but also provides insights into the biological functions and potential pathogenic capabilities of different bacterial species.