A novel technique for estimating the compact myocardium in fishes reveals surprising results for an athletic air‐breathing fish, the Pacific tarpon
Bibliographic record
Abstract
A method for quickly assessing the relative proportion of compact myocardium in the ventricle of teleosts is introduced and used in juvenile Pacific tarpon Megalops cyprinoides , a member of the only air‐breathing elopomorph teleost genus. The proportion of compact myocardium increased with body mass, reaching up to 60% of the ventricular mass. The finding for tarpon was a surprising discovery since recent literature has suggested that air breathing evolved primarily as means of supplying oxygen to the fish heart during activity. The present data, which represent the first quantitative assessment of the compact myocardium for any air‐breathing fish, suggest that myocardial oxygen supply in the tarpon is supplemented by the coronary circulation associated with compact myocardium during exercise, while air breathing is important during aquatic hypoxia. Compact myocardium was also measured as a point of reference in an extant representative from a more ancient fish lineage than the elopomorphs, the water‐breathing spiny dogfish Squalus acanthias and found to be only 9% of ventricular mass. In conclusion, the presence of a coronary circulation in extant elasmobranchs may mean that the coronary circulation evolved well before air breathing in fishes and, for tarpon at least, the coronary oxygen supply to the ventricular myocardium has not necessarily been superseded by air breathing.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".