The sea butterfly - an amazing inhabitant of frigid waters - video

There are animals in the world that are sometimes called sea butterflies. Have you ever heard of such a thing? Or have you been lucky enough to meet them while diving? No? Well, it’s not that simple… all because these creatures are only found in the waters surrounding Antarctica and the Arctic.

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The sea snail limacina helicina, according to researchers from John Hopkins University in Baltimore in a paper in the Journal of Experimental Biology, has been equipped by Nature with specific ‘legs’ at the end of its body. Thanks to this adaptation to life in the sea, they do not swim but float, as if on wings.

After carefully studying the movement dynamics of sea butterflies with an ultra-fast camera, it became clear that the resemblance to insects is unbelievable. The well-known and rather obtrusive fruit fly moves with the help of wings. As it flies, it makes a specific fanning motion, rolling in eights in the air. In this way it generates lifting force. It also has to admit that it flaps its wings quite often, as many as 200 times per second.

Using this camera, the researchers have shown that the sea snail limacina helicina travels through cold waters making exactly the same movements with its ‘wings’. Due to the different density of the water, however, the butterflies only strike 5 times per second.

Presumably, this mechanism emerged independently in the evolution of both insects and molluscs.

When diving in Arctic or Antarctic waters, it is worth looking not only at penguins or sea leopards. It will not hurt to look for underwater butterflies. However, remember that you have to concentrate and look hard, because even though they are predators, it is difficult to spot them. These unusual creatures are very small. They are only 0.5 – 3 mm in size.

Photo: NOAA