HIGH-RESOLUTION FOLDSCOPY OF A BIOLOGICAL MICROMACHINE: VORTICELLA

Our foldscope team was onboard for sampling from Chilika Lagoon along with 6 students and PI of foldscope project from Department of Zoology, D.N. Government College Itanagar, Arunachal Pradesh on 27th Dec 2018. It was a fabulous bright sunny day and we were sure that in our pursuit for capturing the live biological machines in action Chilika and foldscope will not disappoint us. We took a halt at Kalijai, a small island located inside the Chilika Lagoon famous for Goddess Kalijai. We observed dense growth of red and green algae attached to side walls of floating jetty of the island. Students collected some of these algae and on-boat foldscopy unveiled the functioning of a small biological machine: The Vorticella in their natural settings. Foldscopy not only provided a high-resolution real-time imaging of Vorticella that was busy in sweeping food through the movement of its cilia but also other biological communties such as Navicula (a phytoplankton), fish egg larvae, protozoa, rotifer and many more creatures that were busy in running here and there.

Collected algae sample from the jetty to be observed under foldscope.
Movement of Vorticella captured under Foldscope.

Seeing and capturing the functioning of Vorticella, a biological micromachine was a very exciting moment for all of us particularly to our visiting NE partners who were basically B.Sc. Zoology students studied well about these protists but never got a chance to see them in action. Vorticella is a protist (protozoan) and belonging to the Phylum Ciliophora. It has a peculiar inverted bell shaped structure often attached by a long highly contractile stalk to some submerged objects like weeds, animals and stones, algal filaments etc. Adults also swim freely if their stalks are cut, or if they have to detach themselves from the substrate due to unfavourable conditions.  Vorticella are found in freshwater ponds, lakes, rivers and streams. Due to the bell-shaped body it is often called bell-animalcule. The bell-shaped body of Vorticella is attached to weeds or stones by a long, thin, un-branched and highly contractile stalk. Vorticella exhibits high degree of contractility and irritability; it is extremely sensitive to any mechanical stimulus and also responds to external stimuli. When irritated, it’s all activities cease at once; the stalk is retracted and becomes coiled into closed spiral to reduce its size, then the disc is withdrawn and covered over by peristomial lip. There are oral cilia specialized for making water currents that beat to bring food closer to its mouth.

Observance of rotifer, fish egg, phytoplankton around Vortcella under Foldscope.

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