Cannibalism and Interspecific Predation

The cannibalism and interspecific predationlab utilizes both T. thermophila and T. vorax. Morphogenetic change is addressed by observing the T. vorax shift from microstome to macrostome form. As part of the lab, stomatin, the transformation inducing subtance produced by T. thermophila is isolated using simple techniques that can easily be carried out in high school classrooms. The change in morphology is obvious even under relatively low magnification. The lab can be used to address, chemical induction of morphological changes, evolutionary differences among different species within the same genus, and, since the macrostome forms consume their own species as well as (preferably) other Tetrahymena species, inter- and intra-specific predation. The use of inexpensive digital cameras to record morphological changes and predation events adds enormously to student interest and enthusiasm for this exercise.

Cannabalistic Tetrahymena

Module Protocols

High School

Glossary of Terms

Relevant Concepts

Organisms; Relationship of Structure to Function; Mechanisms of Evolution; Population dynamics; Diversity of Organisms; Growth and Survival of Organisms; Diversity and Adaptation of Organisms; Interorganismal Relationships; Species Variation

Next Generation Science Standards Relationships

High School:   |

NYS Science Curriculum Guideline Relationships

Key Ideas | | | |


Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem.
Evaluate the evidence for the role of group behavior on individual and species’ chances to survive and reproduce.
Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors.
Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.
Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.
Apply concepts of statistics and probability to support explanations that organisms with an advantageous heritable trait tend to increase in proportion to organisms lacking this trait.
Evaluate the evidence supporting claims that changes in environmental conditions may result in: (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.
The central purpose of scientific inquiry is to develop explanations of natural phenomena in a continuing and creative process.
Beyond the use of reasoning and consensus, scientific inquiry involves the testing of proposed explanations.
The observations made while testing proposed explanations, when analyzed using conventional and invented methods, provide new insights into natural phenomena.
Living things are both similar to and different from each other and from nonliving things.
Individual organisms and species change over time.