The Capsular Organ of <i>Chelyosoma productum</i> (Ascidiacea: Corellidae): A New Tunicate Hydrodynamic Sense Organ
Bibliographic record
Abstract
Chelyosoma has about 200 sense organs in the atrial wall of the branchial sac that show structural features suggestive of a role in hydrodynamic sensing. They consist of a fluid-filled capsule with an acellular diaphragm spanning an opening in the top. The floor of the capsule is a sensory macula, with 5-6 primary sensory neurons whose cilia project into the capsular cavity and whose axons go to the brain. Animals were tested for vibrational sensitivity using a loudspeaker probe. They responded by muscular contractions of the siphons and/or arrests of the branchial cilia, both of which caused changes in water flow velocity through the siphons, which were monitored non-invasively using a thermistor flow meter. The animals showed peak sensitivity at 240-260 Hz. Subsequent calibration of the loudspeaker probe indicated that the animals could detect 104 decibels re 1 microPa from a source 80 cm away. The majority of axons leaving the capsular organs go to the brain via the visceral nerve. Cutting this nerve abolished or greatly reduced responses. Electrophysiological recordings from the distal nerve stump showed bursts of electrical events following vibrational stimulation. No such records could be obtained from other major nerves and cutting them did not affect responsivity. Corella inflata, a close relative of Chelyosoma, lacks capsular organs and failed to show any responses when the source was more than 3.5 cm away. We conclude that Chelyosoma's vibration-sensing ability is due to its capsular organs and is adaptive in terms of detecting the movements of objects in the vicinity. The findings are discussed in relation to the evolution of hydrodynamic mechanoreceptors in tunicates, amphioxus and craniates.
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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 | 0.000 | 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) | 0.001 | 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".