Confirmation of External Fertilization in the American Lobster, Homarus Americanus
Bibliographic record
Abstract
Fertilization is external in some crustaceans and internal in others. In the nineteenth century, it was reported that the American lobster (Homarus americanus) fertilized its eggs externally using spermatozoa stored in the seminal receptacle. Later investigators questioned this assumption, noting that the spermatophoric mass is sealed inside the seminal receptacle by an impervious sperm plug that prevents the spermatozoa from exiting the seminal receptacle via the orifice. This led to suggestions that fertilization in homarid lobsters is internal via transitory connectives that form between the seminal receptacle and the ovary/oviduct at the time of oviposition. Supporting evidence was obtained from studies in which fertilization occurred even when the orifice of the seminal receptacle was sealed with epoxy. We here report selective occlusion studies that resolve this conundrum. At spawning, spermatozoa leave the seminal receptacle not through the sealed orifice, but via two grooves located posterior and lateral to the orifice. Occluding these posterolateral grooves as well as the orifice of the seminal receptacle prevents fertilization, whereas occluding only the orifice does not. This explains why earlier attempts to prevent fertilization by occluding the orifice of the seminal receptacle were unsuccessful, and confirms that fertilization in the American lobster is external.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".