An assessment of learning modalities in wild-caught freshwater flatworms (Dugesia tigrina)

Abstract

An organism’s ability to learn characteristics of its environment in the presence or absence of certain stimuli is a vital aspect of its survival. However, the level at which certain species can learn is thought to vary along the phylogenic tree. We assess free living freshwater flatworms (Dugesia tigrina) ability to learn via classical and operant conditioning. Flatworms’ ability to learn via classical and operant conditioning was assessed using an electric shock and red light inside an arena. A stronger curling response after training flatworms to associate a red light with a negative stimulus indicates flatworms possess the ability to learn through classical conditioning. Flatworms also actively avoided red light after it was paired with negative stimulus, indicating the capacity for operant conditioning. Despite a primitive nervous system, wild-caught freshwater flatworms exhibit two fundamental forms of learning which could facilitate adaptive foraging and predator avoidance behaviors. In addition, these results add clarity to the debate surrounding the learning capacity within Platyhelminthes and further our understanding of learning among primitive animals.

Key words:

• Platyhelminthes
• operant conditioning
• classical conditioning
• social learning

ACKNOWLEDGMENTS

We thank the Biology Department at Hanover College for funding this research. We also thank Dr Glene Mynhardt for helping to generate the curl scale pictures. Our appreciation to many undergraduate students who helped with animal husbandry and experimentation including Suzie Ronk, Cassie Lutes, Isabella Garino-Heisey, and Ashley Gordon.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.