Notes from Kaziranga, Sohala Beel: Plationus rotifer

Dec 26, 2015 • 4:34 AM UTC

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Microorganisms

laksiyer

Human observer of life. https://sukshmadarshin.wordpress.com

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Sohala (16 in Assamese) Beel (Lake) is a collection of 16 water bodes that form this giant freshwater lake in Kaziranga. On the day of the first workshop, I went to the lake to get some water samples. It was 7:00 am, and all I heard were the call of birds and insects. A lone rhino lazily stared at us as I drove in a jeep along with our driver Pradeep and a guard. The Kaziranga National Park is famous for its large mammals, the endangered one-horned rhino, the elephant, the wild buffalo, many kinds of deer and a variety of birds. The one-horned rhino has been almost poached to extinction and hence any visit to Kaziranga National Park requires you to be with a guard who holds an AK-47 rifle. You cannot walk in the park without permission, or without a guard, and it is shoot at sight if someone is prowling alone. These people protect the jungle as though it is their life, yet there is a tinge of sadness to all this. The guides, drivers and rangers are great fun to interact with as they know each and every living being larger than a mm in size. Pradeep, the driver and guide, spoke about aspects of animal behavior that would make a professional scientist proud. It is now time to introduce them to the microcosmos. I took a few samples for the workshop using a plankton tow. More pics from the workshop will follow in a separate post.
Later that night I got a chance to sit down and image some water samples. This one caught my attention.

At first I thought I saw a dream as I wasnt sleeping much. Only later I realized that it was a loricate rotifer. A lorica is a shell around the rotifer and is often marked by spines and other features. Such external features are used to classify them. Based on these, one can say that this rotifer belongs to the the Brachionid family. More specifically it belonged to the Plationus genus. The animal was smashed between the coverslip and slide and hence I didnt see any movement, although I picked it up because it was moving slowly..
Rotifers have a fascinating aspect called cyclomorphogenesis, where their body shape and proportions change according to seasons, or due to the presence of predators!! Although this rotifer has been recorded in the freshwater lakes of assam (see the monumental work of Sharma and Sharma– a must on everyone’s shelf), I still have a 100 unanswered questions about its life-cycle…
Why does it have such spines? What does it eat? What is its predator? Does it undergo Cyclomorphogenesis? Does it have sexual dimorphisms? What is its seasonal population variation in the Sohala lake? How does it move? … … … 100. Will the foldscopers of Kaziranga study this in great depth?
Note: Rotifer artwork can make a good diversion for kids too.
Reference:
I just realized that there are two great experts of Rotifers and microscopic life in North-east India (Sumita Sharma and B.K. Sharma) and their works are a ready reference and perhaps a must on any shelf studying the microcosmos of fresh water bodies.
Zooplankton diversity in floodplain lakes of Assam : Occasional Paper no. 290. Zoological survey of India. A brilliant monograph
Extensive Bibliography of Sharma and Sharma