https://doi.org/10.5061/dryad.hmgqnk9q5

Corresponding Author: Jarrod Petersen, Brown University, jarrod_petersen@brown.edu
Principal Investigator: Thomas Roberts, Brown University, thomas_roberts@brown.edu

Overview and General Information

This dataset consists of only one type of file which has X and Y marker coordinates obtained from point tracking of light videography. There are at least three trial files per individual (n=6) and sometimes there are more. The "bc00" prefix lists the ID number for the snake which can be referenced to the tables in this document and "PRE" & "POST" refer to the feeding condition (either before or after, respectively). From these coordinates, all of our variables were calculated using simple equations described in the manuscript. Data was recorded at 30 frames per second and the videos were stopped when the snake stopped moving, so each video is not the same length. All numerical values are in millimeters. For further detail on our methodology and for a supplementary video, please refer to our manuscript published in The Journal of Experimental Biology.

Importantly, the following two rules describe how this coordinate data should be treated.

• For a y-coordinate, a more dorsal/superior point will have a lower numerical value than a more ventral/inferior point which would have a higher numerical value.
• For an x-coordinate, a more cranial point will have a higher numerical value than a more caudal point which would have a lower numerical value.

Data-specific Information

For each file there are 16 variables describing the X and Y positions of eight markers, the description of these variables and markers is as follows:

1. marker001_cam1_X, marker001_cam1_Y: Marker 1 is the most dorsal point that is located on a piece of tape sitting just above the most dorsal part of the snake body. X and Y represent the X and Y coordinates of marker 1 over time and cam 1 indicates the camera on the lateral plane.
2. marker002_cam1_X, marker002_cam1_Y: Marker 2 is the second most dorsal point that is located superiorly on dorsal scale row within the range of 17-24. X and Y represent the X and Y coordinates of marker 2 over time and cam 1 indicates the camera on the lateral plane.
3. marker003_cam1_X, marker003_cam1_Y: Marker 3 is the third most dorsal point that is located superiorly on a dorsal scale row within the range of 11-16. X and Y represent the X and Y coordinates of marker 3 over time and cam 1 indicates the camera on the lateral plane.
4. marker004_cam1_X, marker004_cam1_Y: Marker 4 is the second most ventral point that is located inferiorly on a dorsal scale row within the range of 6-8. X and Y represent the X and Y coordinates of marker 4 over time and cam 1 indicates the camera on the lateral plane.
5. marker005_cam1_X, marker005_cam1_Y: Marker 5 is the most ventral point that is located inferiorly on dorsal scale row 3. X and Y represent the X and Y coordinates of marker 5 over time and cam 1 indicates the camera on the lateral plane.
6. marker006_cam2_X, marker006_cam2_Y: Marker 6 is located on the underside/belly of the snake on the cranial-most ventral scute of a three-scute-pair. This scute pair is directly underneath markers 1-5. X and Y represent the X and Y coordinates of marker 6 over time and cam 2 indicates the camera on the ventral plane, looking up from below at the underside of the snake.
7. marker007_cam2_X, marker007_cam2_Y: Marker 7 is located on the underside/belly of the snake on the caudal-most ventral scute of a three-scute-pair. This scute pair is directly underneath markers 1-5. X and Y represent the X and Y coordinates of marker 7 over time and cam 2 indicates the camera on the ventral plane, looking up from below at the underside of the snake.
8. marker008_cam2_X, marker008_cam2_Y: Marker 8 is located on the lateral skin of the snake at a marker located approximately at the midline. X and Y represent the X and Y coordinates of marker 8 over time and cam 2 indicates the camera on the ventral plane, looking up from below at the underside of the snake. This marker is exclusively used to measure cyclic changes in muscle width (∆W).

As some markers (2-5) give a range of dorsal scale rows they were attached to, a complete list per individual is below: