Buzz Blog

The Beauty of the Sea Butterfly's "Flight"

Tuesday, March 01, 2016

Flight has evolved independently at least three times, by three different animal groups: birds, bats, and insects. Now, a team of researchers at Georgia Tech has confirmed that a species of aquatic snail, the "sea butterfly" Limacina helicina, flaps its wing-like appendages the same way that some small insects use their wings to fly.
Image Credit: Russ Hopcroft, Institute of Marine Science, University of Alaska Fairbanks (UAF); and NOAA
“In a remarkable example of convergent evolution, we show that the zooplanktonic sea butterfly Limacina helicina ‘flies’ underwater in the same way that very small insects fly in the air,” they write in the Dec. 8, 2015, issue of the Journal of Experimental Biology. Insects diverged from gastropods, such as snails and slugs, approximately 550 million years ago.

The motion that L. helicina (and likely some shell-less marine mollusks like Clione limacina and Clione antarctica) shares with small flying insects is the Weis-Fogh or “clap-and-fling” mechanism. This involves a wing stroke that moves in a “figure-of-eight pattern to produce lift, and both generate extra lift by peeling their wings apart at the beginning of the power stroke,” the Journal of Experimental Biology article says. This is unlike most zooplankton, which use their appendages as paddles in a more traditional swimming motion.