A riddle, wrapped in a mystery, inside a barnacle
Bibliographic record
Abstract
Approximately 80% of barnacles in Burrard Inlet, British Columbia, Canada, are infected with metacercariae, a life stage of the trematode Maritrema gratiosum, but the origin of these infestations is unknown. Trematode parasites have a three-host life cycle and six distinct life stages. Adults usually infect shorebirds, which release the parasites’ eggs in their feces; these eggs subsequently metamorphose into miracidia, which then infect snails. At this point, the miracidia develop into sporocysts that asexually produce thousands of free-swimming larvae (cercariae), which emerge from the snails. The cercariae then locate and infect the next host (a bivalve, a barnacle or other type of crustacean, or a fish) and form a metacercaria, protected by a spherical cyst, in their soft tissue (note: all three images show M gratiosum metacercariae embedded in barnacle tissue). In the final stage of the life cycle, a shorebird eats an infected host and the metacercariae hatch into the next generation of adults. Given the high proportion of infected barnacles in Burrard Inlet, and the density of metacercariae (typically in the hundreds) contained within them, it is a mystery as to why there are no records of snails infected with M gratiosum at this location. Likewise, surveys at other sites of heavy barnacle infections have failed to detect substantial numbers of infected snails. One answer to this puzzle may be that the cercariae are transported over long distances by tidal currents and the infected snails (the sources of the cercariae) are relatively far away. Alternatively, these metacercariae may persist and remain viable for months or even years, such that even a relatively small number of infected snails could produce enough cercariae to infect millions of barnacles over time. Given that cercariae are known to transmit many diseases to humans (eg schistosomiasis), our barnacle mystery provides a great opportunity to study the dispersal patterns of a disease-causing agent.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.004 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.051 | 0.015 |
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".