Swarthmore College 2 articles published in JoVE Biology Thermal Limits Determination for Zooplankton Using a Heat Block Kit Yu Karen Chan1, Benjamin K. Jorgensen1, Samuel Scoma1 1Biology Department, Swarthmore College The present protocol illustrates the use of commercially available components to generate a stable and linear thermal gradient. Such gradient can then be used to determine the upper thermal limit of planktonic organisms, particularly invertebrate larvae. Biology Planarian Scrunching as a Quantitative Behavioral Readout for Noxious Stimuli Sensing Ziad Sabry1, Christina Rabeler1, Danielle Ireland1, Kevin Bayingana1, Eva-Maria S. Collins1,2 1Biology Department, Swarthmore College, 2Physics Department, UC San Diego Freshwater planarians exhibit three gaits (gliding, peristalsis, and scrunching) that are distinguishable by quantitative behavioral analysis. We describe a method to induce scrunching using various noxious stimuli, quantification thereof, and distinction from peristalsis and gliding. Using gene knockdown, we demonstrate the specificity of scrunching as a quantitative phenotypic readout.