Sixteen individuals of Pleurobrachia bachei, ranging from 4.6 to 13 millimeters (mm) in length, were collected with a 0.5-meter (m) ring net with 500-micrometer (μm) mesh, or by hand collecting in jars, from Coos Bay, Charleston, OR, in July 2018. Organisms were stored in 1-liter containers for no longer than 1 week at ambient field temperatures (11 to 14 degrees Celsius). Individuals were filmed in a glass vessel (350 cubic centimeters (cm^3)) for 15 minutes in a dark-field setup using a Sony camcorder (HDR-CX900) at 60 frames per second, and video analysis was done using ImageJ. The tank volume to ctenophore volume ratio was approximately 700:1, and ctenophores exhibited normal swimming behavior during the video trials. Morphometric parameters, including ctene length, spacing (distance between ctenes), row length, and number of ctenes per row, were also measured for each organism.

Two individuals of P. bachei were hand-collected from the docks at Friday Harbor Labs (FHL), WA, in June 2017 for more detailed kinematics. Ctene width and tip speed over time were measured using high-speed microvideography recorded at 1,000 frames per second in 2,048 × 2,048-pixel resolution (Photron Fastcam Mini WX100). Ctene width was measured at the inflection point of the ctene, typically 30 to 40 percent of ctene length from the tip, because this portion changed dynamically during the pulse cycle.