Abundance survey of crustacean “y-larvae” (Thecostraca: Facetotecta) over a fringing reef in Okinawa, Japan, with special reference to the two dominant planktotrophic and lecithotrophic naupliar types
Bibliographic record
Abstract
Abstract Facetotecta, or “y-larvae”, are mysterious planktonic crustaceans that are known only from their larval instars, but which are often assumed to be endoparasitic as adults. Dozens of mostly undescribed forms occur in the shallow-water plankton over a fringing reef at Sesoko Island, Okinawa, Japan. Recently, it has become possible to discriminate the different forms of their nauplius-stage larvae (“y-nauplii”) in a replicable way. A large year-to-year overlap in morphospecies recovered during fieldwork at Sesoko Island in 2018, 2019, and 2023 suggests that a full inventory is close at hand. To date, 49 morphospecies of y-nauplii (8 planktotrophic, 41 lecithotrophic) have been recognized in the area, among which three have been formally described. A detailed analysis of the temporal fluctuations in abundance during October 2023 showed that most morphospecies were rare, but two were particularly common: Type A*, a planktotroph with a long (> 3 weeks) period of naupliar development allowing for long-distance dispersal, and Type AG*, a lecithotroph with a short (3 days) period of development that implies rapid local recolonization. During the survey, both types showed distinct, largely non-overlapping peaks in abundance, related perhaps to their different dispersal/feeding strategies. An examination of the morphology of the swimming/feeding appendages in y-nauplii of Types A* and AG*, together with a mapping of feeding versus non-feeding nauplii on a recent comprehensive phylogeny of Facetotecta, suggests that broader taxonomic coverage of naupliar feeding structures in this group may provide useful information regarding the evolutionary direction of planktotrophy versus lecithotrophy in marine larvae.
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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 | 0.001 |
| Science and technology studies | 0.001 | 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".