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natural history: rotifers

bdelloid rotifers


Unidentified bdelloid rotifer with head poking out of peanut shaped liverwort lobule

We were trying to take micrographs of the minute liverwort Frullania rostrata when we discovered movement amongst the leaves. About half of the lobules contained minute creatures which poked their heads out and gave the appearance of twirlling batons.

By sheer luck we came across an article describing pond life and we were able to identify the creatures as bdelloid rotifers. They are the smallest of animal life comprising of a thousand cells or so, and measuring a scant 25 um (0.025 mm) wide near the head, and possibly several times that in length. We observed one outside a lobule and the best way to describe it is in terms of several conjoined blobs. Its movement was similar to that of leeches, with head grabbing contact then tail following to a closer point.

Bdelloid rotifers are all females capable of reproducing through parthenogenesis (without fertilization) and are able to survive dessication and freezing for considerable periods to revive when water becomes available.

A search on the web confirmed that rotifers have been reported to live in Frullania lobules elsewhere in the world. Whether they have been reported to live in F. rostrata lobules in Tasmania, and if these have been described is a matter we are unable to ascertain.

- Glime, J. has published a lengthy chapter on rotifers in her online book
- Micrographia has some detailed images.
- Bdelloid rotifers - 80 million years without sex
- for superb rotifer micrography visit

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