Proboscis

This moth was probably a football fan. It flew in while we were watching one of the World Cup matches, and hid behind a curtain all night. Although this type is common in Mumbai, like most moths it has no common name. So I’m forced to call it the Pygospila tyres. I’ve seldom noticed the proboscis of moths, but here the coiled organ was so visible that the photos I took are concentrated on this. The proboscis is a tube which combines the functions of a drinking straw and a sponge for mopping up fluids. Ray Cannon has a very nice blog post on the proboscis of butterflies.

Scientists love to group all moths and butterflies together and call them Lepidoptera. This is useful because they have many features in common. All Lepidoptera which have proboscis are called Glossata. I didn’t think there was any need to have a new word for this; don’t all Lepidoptera have proboscis? After all, since the time of Darwin, people have studied how flowers and proboscis have shaped each other. You might be as surprised as me to read that there are some, although very few, moths without this organ. Some of them have mouths designed to masticate pollen, and some finish all their eating while they are caterpillars!

The proboscis is weirder than I’d ever thought about. Once it is uncoiled, Lepidoptera suck up fluids using muscles analogous to those in our cheeks and throats, so a drinking straw is not a bad description of it. Uncoiling uses a mechanism similar to erectile tissue in our bodies, in the sense that body fluids are pumped into the organ to flex it. Moreover, the adult stage of the insect forms the proboscis after it has emerged from its cocoon by fusing together two different appendages. But the oddest thing is that there are flexible sensory organs all along it (think of sensitive fingers) which give the insect a clear picture of the shape of the flower that it is probing.

Further searches led me to even stranger information. It seems that fossils of Glossata have now been found which are 212 million years old. This was a time when flowering plants had not yet evolved, so what use would there be for this organ? It seems that the era during which the newly discovered fossils lived was a time of ecological crisis. The ancient super-continent of Pangaea was beginning to break up and the atmosphere was full of greenhouse gases from the volcanoes which were tearing apart the continent. In this hot dry atmosphere water loss from the body would have been a major issue, and proboscis could be used to lap up even minute quantities of fluids. Even today Glossata ingest fluids from puddles of mud, mammalian sweat and avian tears.

The football fan was not interested in my tears or sweat. When I opened the window and flicked it off the curtain it disappeared into vegetation with strong beats of its wings.

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Author: I. J. Khanewala

I travel on work. When that gets too tiring then I relax by travelling for holidays. The holidays are pretty hectic, so I need to unwind by getting back home. But that means work.

5 thoughts on “Proboscis”

  1. Feeling nostalgic with those terms – Lepidoptera, probscis, etc 😀
    I have done my masters in Zoology but landed up in an unrelated profession and have been away from the subject for more than a decade now!

    Like

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