Walking

The X-ray animal walks to a real recording. We gave it eight legs and played back every touch-down and lift-off, step for step, as Ian Woods' lab marked them frame by frame in video.

The data

The steps come from Anderson et al. 2024, a comparison of adult and juvenile H. exemplaris, another species (Ramazzottius) and animals treated with disulfiram, with code and spreadsheets on GitHub. We used its sample clip, which has every step of all eight legs, the tracked body path and the video itself, and its comparison sheets: each group's average stance and swing times, the offsets between neighbouring legs, and step length.

Putting legs on the scan

We built the legs from the scan itself. Each foot is marked by a claw gland, so the claw glands gave us eight feet, and we placed a hip above each. Left and right mattered, and the scan doesn't say which side is which, so we used the anatomy: the ovary lies on the animal's left (Gross et al. 2019), which fixed the sides. Each leg's skin, claw gland and muscles bend around its hip by distance, so a leg swings forward and plants.

Two ways to walk

• The recording: every lift-off and touch-down happens when the lab marked it, and the body moves at the tracked speed. The source video can play alongside.
• Group averages: a steady walk built from each group's measured means: adults, juveniles, Ramazzottius, controls and disulfiram-treated animals.

What's uncertain

• Legs bend around one hip joint, not the real segments.
• The recorded animal was 222 µm long; the scanned one is 152 µm, so steps are scaled by body length.
• Organs inside the legs don't follow yet, and there's no turning.

Try it: the glass tardigrade, walking. The step data as we used them are on Resources.