Unique Two-Photoreceptor Scanning Eye of the Nematode<i>Mermis nigrescens</i>
Bibliographic record
Abstract
A single eye is present in females of the nematode Mermis nigrescens. A pigment cup occupies the entire cross section near the anterior tip of the worm, and the curved cuticle at the tip becomes a cornea. The shading pigment is hemoglobin instead of melanin. The eye has been shown to provide a positive phototaxis utilizing a scanning mechanism; however, the eye's structure has not been sufficiently described. Here, we provide a reconstruction of the eye on the basis of light and electron microscopy of serial sections. Hemoglobin crystals are densely packed in the cytoplasm of expanded hypodermal cells, forming the cylindrical shadowing structure. The two putative photoreceptors are found laterally within the transparent conical center of this structure where they would be exposed to light from different anterior fields of view. Each consists of a multilamellar sensory process formed by one of the dendrites in each of the two amphidial sensory nerve bundles that pass through the center. Multilamellar processes are also found in the same location in immature adult females and fourth stage juvenile females, which lack the shadowing pigment and exhibit a weak negative phototaxis. The unique structure of the pigment cup eye is discussed in terms of optical function, phototaxis mechanism, eye nomenclature, and evolution.
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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) | 0.001 | 0.000 |
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".