Theory 13/Deep scattering layer/Rate lens
Migration Tracks Light Change
The claim
The speed of diel vertical migration is set by the rate of change of light at depth rather than by absolute light level.
01Mechanism
Animals track an isolume; the rate at which that isolume moves sets how fast they must swim to stay with it.
02Prediction
Migration speed should track light change rate.
03Refutation
Speed tracking light level would remove the derivative.