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== Behavior and distribution ==
Molluscan pteropods develop their feet into a pair of wing-like (parapodia) in the growing phase. The wings are highly flexible because the orientation of the muscles is different and have a hydrostatic skeleton filled with pressurized fluid. Therefore, the high bending angle supports the parapodia to diminish the drag forces generated by the classic clap-and-fling maneuver; it also, helps to carry the extra weight of the shell and ascend in the water column for the diel vertical migration.<ref>Karakas, F., Maas, A. E., & Murphy, D. W. (2020). A novel cylindrical overlap-and-fling mechanism used by sea butterflies. Journal of Experimental Biology, 223(15), jeb221499.</ref>
The power stroke for ''L. helicina'' starts with a sharp rotation of it is body accompanied by an increase in swimming speed, then ''L. helicina'' rotates the shell in the opposite direction to initiate the recovery stroke and swims upward with a speed less than the power phase. There is a drop in swimming speed between power and recovery strokes which develop a sawtooth trajectory in the sagittal plane. The hyper-pitch of the round shell of ''L. helicina'' diminishes the rotational drag and the moment of inertia; also, the extreme shell rotation assists in raising the wingtips at the end of each stroke to create a figure-of-eight pattern, which is common for aerial insects. In contrast, flying insects and shell-less pteropods encounter higher resistance forces that limit the body rotation.<ref>Murphy, D. W., Adhikari, D., Webster, D. R., & Yen, J. (2016). Underwater flight by the planktonic sea butterfly. Journal of Experimental Biology, 219(4), 535-543.</ref>
Sea butterflies range from the tropics<ref name=ParraFlores2009/> to the poles.<ref name=Seibel2007/>
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