Becoming an Ecologist:
Investigation Into The Life Cycle Of The 17-Year Cicada
Information for teachers
by Kathleen Moran (
This lab is meant to help students gain experience and develop an understanding of elements of scientific inquiry through the study of an ecological phenomenon. It can be a good way to introduce or conclude an ecology unit.
This lab is written specifically for ninth and tenth grade living environment classes. However, it can be used in any biology class that include a unit on ecology and/or require an understanding of the scientific process and the nature of that process.
Two consecutive days
Magicicadas are a genus of cicadas that emerge from the ground every seventeen years. They emerge only to find a mate and reproduce. They die shortly after this objective is accomplished. When cicadas finally do emerge, they emerge by the millions in many areas. In observing this ecological phenomenon, scientists developed a hypothesis to explain this life cycle strategy. This hypothesis is called the predator satiation hypothesis. It states that a large population decreases the per capita chance of predation for individuals. Since cicadas have no anatomical defense mechanisms, strength in numbers is an important survival strategy for the species.
Testing this hypothesis can easily be done in a classroom environment. Using popcorn kernels or anything similar, students can test how many kernels get preyed upon as different amounts become available. The relationship that will be observed is that the number of kernels preyed upon will increase as the number available increases and eventually level off. The percentage of kernels preyed upon will decrease as the population increases.
This lab is written to familiarize students with many of the elements of scientific inquiry, as well. It also requires students to begin thinking about ecological concepts such as competition, predation and defense.
Learning and Behavioral Objectives
o Students’ answers to the lab should be looked at.
o Their ability to complete part 2 of the lab will be based on their understanding of part one.
o A discussion of the discussion questions and results could help the teacher get all the objectives across