Morphological adaptation of the sand dollar Echinarachnius parma to its environment
Bibliographic record
Abstract
The common sand dollar Echinarachnius parma from eastern Canada, in addition to showing marked changes in the camber of the aboral surface related to the strength of wave and current activity, shows sexual dimorphism in the shape of the oral surface. The oral surface is more concave in males than in females. This dimorphism develops as individuals become sexually mature and is pronounced for individuals measuring >40 mm in diameter. Associated with this shape difference, the volume of females is greater than for the males and this corresponds to the larger size attained by the ovaries compared to the testis. Shape differences between males and females are rare in echinoderms and E. parma is the first species for which the sexes can be separated with a high degree of accuracy (>80%) on the basis of shape. Whereas the radial symmetry of the sand dollar E. parma is striking, we show that the mass and thickness of the anterior portion is greater than for the posterior portion. By adding weights to either portion and quantifying the rising response, we demonstrate that the asymmetry in body mass is required for the sand dollar to right itself.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".