Planarian Phototactic Assay Reveals Differential Behavioral Responses Based on Wavelength

PLoS One. 2014 Dec 10;9(12):e114708. doi: 10.1371/journal.pone.0114708. eCollection 2014.

Abstract

Planarians are free-living aquatic flatworms that possess a well-documented photophobic response to light. With a true central nervous system and simple cerebral eyes (ocelli), planarians are an emerging model for regenerative eye research. However, comparatively little is known about the physiology of their photoreception or how their behavior is affected by various wavelengths. Most phototactic studies have examined planarian behavior using white light. Here, we describe a novel planarian behavioral assay to test responses to small ranges of visible wavelengths (red, blue, green), as well as ultraviolet (UV) and infrared (IR) which have not previously been examined. Our data show that planarians display behavioral responses across a range of wavelengths. These responses occur in a hierarchy, with the shortest wavelengths (UV) causing the most intense photophobic responses while longer wavelengths produce no effect (red) or an apparent attraction (IR). In addition, our data reveals that planarian photophobia is comprised of both a general photophobic response (that drives planarians to escape the light source regardless of wavelength) and wavelength-specific responses that encompass specific behavioral reactions to individual wavelengths. Our results serve to improve the understanding of planarian phototaxis and suggest that behavioral studies performed with white light mask a complex behavioral interaction with the environment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Eye / radiation effects
  • Infrared Rays
  • Ocular Physiological Phenomena
  • Photic Stimulation / methods*
  • Planarians / physiology*
  • Planarians / radiation effects
  • Ultraviolet Rays

Grants and funding

This work was supported by a start-up grant from Western Michigan University to WB and a Faculty Research and Creative Activities Award from the Office of the Vice President for Research at Western Michigan University (W2013-007) to JJ. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.