Tardigrades survive near-total water loss by replacing lost water's structural role with trehalose sugar and intrinsically-disordered CAHS proteins, which solidify into a molecular glass — the vitrification hypothesis of anhydrobiosis (Crowe et al.).
This 2D build renders that same physics two ways at once instead of a 3D tardigrade body: a live phase diagram (top) plotting the Gordon-Taylor glass-transition curve Tg(w) against the current ambient temperature and water content, and a 2D random-walk field (bottom) of biomolecules whose step size is set by a diffusion coefficient that is derived from the same mobility factor:
T_g,mix = (w_w·T_g,water + K·w_s·T_g,solute) / (w_w + K·w_s)
mobility(T) = 1 / (1 + exp(-(T_amb - T_g,mix)/5)) — logistic, same as the 3D build
D(t) = D0 · mobility(t) — Stokes-Einstein-style: mobility ⟺ diffusivity
w_w = water mass fraction, w_s = solute mass fraction = 1 − w_w
T_g,water ≈ −137°C, T_g,solute ≈ +115°C, K ≈ 4.7 (Gordon-Taylor, trehalose-water)
Each particle in the lower field performs an independent Brownian random walk with per-step variance 2·D·dt (2 spatial dimensions). The panel tracks the ensemble's mean-squared displacement over a short rolling window and back-solves it for a measured D, so you can watch the measured diffusivity collapse toward zero — matching the predicted D0·mobility — exactly as the cytoplasm vitrifies. Above the panel, the phase-diagram dot traces (w, T) live against the T_g(w) curve: the dot crossing below the curve is the same vitrification event, shown as a state-space transition instead of a color change on a 3D mesh.
- Desiccation rate — how fast body water evaporates once "Desiccate" is active.
- Ambient temperature — the horizontal reference line on the phase diagram, compared against T_g,mix each frame.
- Trehalose / CAHS level — sets the dry-solute mass fraction, which reshapes the whole T_g(w) curve.
- Amber, jittering particles = mobile (at risk if also dehydrated); cyan, still particles = vitrified and protected.
- The "vulnerable window" is low water content before vitrification catches up — visible on the phase diagram as the region where the state dot is left of the curve's steep rise but still above it.