Analysis of the mero-carpopodite joint of the American lobster and snow crab. II. Kinematics, morphometrics and moment arms
Bibliographic record
Abstract
This research reports on the kinematics of lobster and snow crab walking, documents changes in the moment arms of the mero-carpopodite joint during rotation, and examines scaling effects of morphological and mechanical variables in these crustacean species. Forward walking lobsters and lateral walking crabs were recorded and images analysed to describe the kinematics of these animals, and subsequently morphometric and moment arm measurements made. During forward walking the lobster maintains fixed mero-carpopodite joint angles during both the power and recovery strokes, though each of the walking legs maintains different joint angles. Legs 3 and 5 are maintained at angles which appear to equalize the flexor and extensor moment arms, and leg 4 joint angle appears to maximize the extensor moment arm. The snow crab has a joint excursion angle of between approximately 50° to 150° and, during flat bed walking, the leading and trailing legs move through similar excursion angles. The length of the meropodite for both species are longer for the anterior two leg pairs relative to the posterior two pairs and the rate of growth of the meropodite is largely isometric for the lobster while consistently increases with positive allometry in the crab. The flexor and extensor moment arms generated as the joint undergoes flexion/extension show two distinct patterns with the extensor moment arm being maximized at relatively low joint angles (55°–115°) and the flexor moment arm reaching a plateau at joint extension with angles between 95° and 155°. The flexor apodeme possesses the largest moment arms in all legs for both species, suggesting the flexors are able to generate greater torques. It appears that, mechanically, these laterally moving animals may be ‘pulling’ with the leading legs to a greater extent than ‘pushing’ with the trailing legs.
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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 | 0.000 | 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".