The medusæ do not usually direct their movements to favorable locations but continue swimming at random until they come into an optimum environment, where they settle down. 2. Intense light turns medusæ away, thus avoiding injury. 3. Change of light intensity is the stimulus for reactions to light. In pronounced decrease, the change of intensity causes inhibition. 4. Relative intensity in the field, not ray direction, determines the place of rest. 5. Light is necessary for the up-swimming activity, though not directive—this being due to gravity. 6. Contact of the bell with air and the accompanying recoil probably causes the inhibition that precedes inversion of the bell at the surface.
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Louis Murbach (1909) studied this question.