Bacterial Shape Classification

Contributor: Felicia Sabur. Lesson ID: 11646

You can often tell the make of a car by its shape. That also works for fruit, vegetables, viruses, and bacteria as well! See how this helps medical workers get you back in shape when you are infected!


Life Science

learning style
personality style
Grade Level
High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!


After the major earthquake in Haiti in 2010, many people became sick. How did an earthquake cause people to get sick?

The medical personnel quickly realized it was cholera, caused by the bacteria vibrio cholerae.

Vibrio cholerae bacteria are found in brackish water. When people came in contact with the contaminated water, they became infected. Doctors and researchers were able to identify the bacteria and implement treatment plans.

Before moving on, if you missed, or need to review, the previous five Related Lessons in this Viruses and Bacteria series, find them in the right-hand sidebar.

Bacteria are mighty little microbes that come in many shapes, which allows doctors and researchers to quickly identify the more common bacterial diseases. Bacteria can be classified two ways: by shape and by organization in groups. The most common shapes are the coccus, bacillus, and spirillum, but there are many more bacterial shapes overall. The image below shows six of the more common shapes:

common bacteria shapes

Bacteria are also classified by organization in groups. The prefix "Diplo-" means two, which means they come together in pairs. The prefix "Staphylo-" refers to grape-like, which means they come together in clusters. The prefix "Strepto-" means "in chains," which means that the bacteria come together in straight lines.

A pair of coccus-shaped bacteria would be called "diplococcus."

  • What would a pair of bacillus-shaped bacteria be called?

A chain of bacillus is called "streptobacilli."

  • What do you think a chain of coccus would be called?

Use the illustration below to check to see if you were correct:

bacteria types

Fill in the blanks and answer the questions for Lesson Six, Bacterial Shape Classification, in your Viruses and Bacteria Unit Workbook, as you watch the video on bacteria classification below. If you didn't print out this resource in Lesson One, please download and print it from Downloadable Resources in the right-hand sidebar.

Bacteria Classification by Shape, by Biology Professor:


Discuss with your teacher or parent why it is important for doctors to be able to use these methods to identify bacteria.

Bacteria are classified by their shape and how they organize themselves into groups. This makes it easier and quicker for medical personnel to identify what bacteria may be infecting a person.

In the Got It? section, you will review all five shapes and three ways bacteria organize by groups, while making a slide show presentation.

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