Cuttlefish hunting a crab face a defended target with good motion detection. Sepia latimanus advances slowly with its first arm pair raised and passes bands of dark chromatophore expansion down the body towards the arm tips, a display often called passing cloud.
Work published by Matteo Santon and colleagues tested what this does to the prey. Crabs presented with an approaching cuttlefish showed weaker defensive responses when the display was running than when the same approach lacked it, consistent with the moving pattern masking the looming visual signal a crab would otherwise use. In effect the display substitutes visual motion on the predator's own skin for the motion of its approach.
Two caveats belong with this. The display is not unique to Sepia latimanus, and similar passing patterns are reported in other cuttlefish and in some squid, so it is not a single-species trick. And the older interpretation, that the display is meant to mesmerise or hypnotise the prey, does not describe a mechanism. What the evidence supports is sensory interference, not a trance.