Domain: Natural Science — Ecology & Evolutionary Biology
Target concept: Flatfish on sandy bottoms gradually match the color and spot pattern of the sand.

Video generation prompt: On the sandy seabed, a flatfish lies motionless amid mottled, diverse sand patterns.

Evaluation guide:
(i) Target concept: Adaptive background matching via dynamic chromatophore response in flatfish.
Minimum mechanism: Flatfish must be physiologically capable of real-time pigment dispersion/contraction and pattern reorganization in response to visual input of substrate; substrate must be heterogeneous and mottled to drive pattern replication, not just uniform color shift.
(ii)Storyline: Frame 0–2: Flatfish clearly visible (distinct color and discrete spot pattern against sandy background with visible mottling). Frame 3–7: Progressive color convergence and spot pattern diffusion/rearrangement, increasingly mirroring sand’s tonal variation and spatial irregularity. Frame 8–10: Full perceptual fusion (no detectable boundary, contrast, or pattern discontinuity between flatfish skin and adjacent sand); viewpoint remains fixed, overhead or oblique, with consistent shallow-water optical properties (e.g., subtle light scatter, no refraction distortion).

Manual:
Experimental Procedure
1. Place a live flatfish on a natural sandy seabed.
2. Observe motionlessly for 10 seconds without disturbance.
Observation of Experimental Phenomena
Flatfish initially contrasts with sand in color and spot pattern; over time, its skin color shifts and its spots reorganize to replicate the mottled, diverse texture of the surrounding sand—until its outline becomes visually imperceptible.
Summary of Experimental Principles
Flatfish possess chromatophores and dermal structures enabling rapid, neurally controlled adaptive coloration and pattern mimicry—a survival adaptation for crypsis on variable sandy substrates.

Prompt Grounding rubric:
level_1: No flatfish appears in the scene; there is no sandy seabed; the substrate shows no mottled, multi-toned pattern; the setting is unrelated to a marine benthic environment (e.g., open water, a bare tank, or dry land).
level_2: A fish-like shape appears but is not built like a flatfish: it swims upright with a normal, laterally symmetric body rather than lying flattened on the bottom; or the seabed is rocky, muddy, or otherwise clearly not sand; or the visible substrate is a single uniform tone with no mottling.
level_3: A flatfish with a visibly flattened, laterally compressed body lies on a sandy seabed whose surface shows mottled, multi-toned grain patterning; the flatfish is stationary and in contact with the substrate at the start of the clip; the camera holds one fixed view of the scene without cutting or panning to a different angle.
level_4: All the level-3 setup elements are rendered clearly: the flatfish's flattened body is unambiguous, the sand's mottled, multi-toned grain pattern covers most of the visible substrate, and the flatfish stays in the same spot and posture on the seabed for the whole clip; but one minor setup detail is off, such as the water and lighting reading more like a shallow aquarium than an open seabed, or the sandy patch being noticeably smaller than the frame.
level_5: The flatfish's flattened, laterally compressed body rests motionless in full contact with a sandy seabed whose mottled, multi-toned grain pattern fills the frame, and the camera keeps one unbroken, fixed view of the scene for the entire clip; this setup fidelity is judged on its own terms, independent of whether the flatfish's color and pattern subsequently come to match the sand, which is scored separately under the science rubric.

Scientific and Causal Correctness rubric:
level_1: No adaptive color or pattern change occurs in the flatfish; its skin tone and spot pattern stay fixed while the surrounding sand is visibly different in color or grain (e.g., the flatfish stays uniformly dark on pale sand, or uniformly pale on dark, mottled sand), showing no causal link between the flatfish's chromatophores and the substrate it rests on.
level_2: The flatfish's color does shift, but in the wrong direction for the sand it rests on (e.g., it grows paler while lying on darker sand, or darker while lying on paler sand); or its spots reorganize into a pattern whose scale or arrangement bears no relation to the sand's mottling; no progression from an initial mismatch toward a matching end-state is visible.
level_3: The flatfish starts with an obvious color and spot-pattern mismatch against the sand; by the end it shows only partial convergence: for example, its head region approaches the sand's tone while its tail stays noticeably darker or lighter, or its overall color matches but its spots remain coarser or more discrete than the sand's fine mottling.
level_4: The flatfish starts with a clear color and pattern mismatch and shows continuous, progressive convergence toward the sand's appearance; by the final frame its base color matches the sand and its spot pattern echoes the sand's mottled variation, but one localized feature (such as the sharpness of its body outline or the scale of a few spots) still reads as slightly different from the surrounding grain.
level_5: The flatfish starts with an unmistakable color and pattern mismatch against the sand, then its base color and spot pattern shift continuously and smoothly throughout the clip; by the final frame its color tone, spot scale, and spot spacing closely track the sand's mottled variation across its whole body, so that a viewer's eye can no longer find any patch of the flatfish that stands out in hue or pattern density from the adjacent sand.

Spatiotemporal Consistency rubric:
level_1: The flatfish's position, size, or orientation changes abruptly between frames (e.g., it jumps to a different spot on the seabed, flips onto its side, or suddenly looks larger or smaller); the sand's grain pattern resets to a different arrangement partway through the clip; or the shadow cast by the flatfish swings to a different direction or brightness between frames with nothing else in the scene to explain the change.
level_2: The flatfish stays near the same spot but moves unnaturally: for instance it pulses, bobs up off the seabed, or vibrates in place; the sand's mottled pattern visibly slides or warps across several consecutive frames; or the shadow beneath the flatfish brightens and dims inconsistently through the clip even though nothing else in the scene changes.
level_3: The flatfish holds a fixed position and posture on the seabed, the sand's grain pattern is continuous and stable, and the shadow beneath the flatfish stays anchored to one direction and brightness throughout, but a rendering flaw recurs at more than one point in the clip: for example, a patch of sand blurs and loses its grain detail for a couple of seconds on two separate occasions, or a section of the flatfish's edge flickers against the sand more than once.
level_4: The flatfish's position, posture, and scale stay constant throughout, the sand's mottled grain pattern is continuous and stable across the whole substrate, the shadow beneath the flatfish holds one direction and brightness, and the camera framing never cuts or jumps; only one small, brief flaw remains: for example, a single patch of sand looks blurrier or flatter than its surroundings for a couple of seconds before resolving, with nothing else amiss elsewhere in the clip.
level_5: The flatfish remains fixed in position, posture, and scale for the entire clip with no drift, jitter, or bobbing; the sand's mottled grain pattern is continuous and evenly detailed across the whole substrate with no warping, sliding, blurring, or texture loss anywhere; the shadow beneath the flatfish holds a constant direction and brightness from start to end; and the camera keeps one unbroken framing of the scene throughout.