Internal fertilization in the salp <i>Thalia democratica</i>
Bibliographic record
Abstract
Among tunicates, gamete morphology and sperm–egg interactions have been extensively investigated in ascidians, and to a lesser extent in appendicularians and thaliaceans. Sperm–egg interaction has been studied in only one salp, Pegea socia (Bosc, 1802). To determine if the pattern of internal fertilization of P. socia is generally applicable to salps, we performed an ultrastructural study on blastozooids of Thalia democratica (Forsskål, 1775). The ovary, located in the mantle near the gut, consists of a single oocyte connected to the atrial chamber wall by a “fertilization duct”, resembling a stack of single cells without a lumen. The flagellate sperm has a long corkscrew-like head with the single mitochondrion twisted around the nucleus. Fertilization is internal, and sperm actively penetrate the atrial wall and bore through the cells of the fertilization duct. During this process, the fertilization duct shortens as the cells move apart, one to one side and the next to the other, and rejoin to form a central lumen, which contains many sperm. At the same time a few sperm reach the periovular space for fertilizing the oocyte. Comparisons with P. socia indicate that this singular mode of internal fertilization with a complex corkscrew sperm actively penetrating the fertilization duct cells, probably evolved in the salp ancestor and has been modified to some extent in various genera.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".