A water lily inhabitant - Dactylobiotus dispar

Do you like ponds? Just look out for a nearby pond with romantic water lilies.

Water lily leafs in various colour shades.

Water lilies are not only beautiful to look at. Moreover some tardigrades make use of their undersides as preferred habitats.
Dear microscopists, please take care to respect the integrity of those magnificent green water lily leafs and do restrict your experimental work to the isolated parts of partially rotten water lily leafs!
Even at moderate magnifications it will become apparent that those water lily leaf undersides are veritable artworks by nature:

Underside of a partially decayed water lily leaf.

Magnificent colours.

Image width 2 mm.

From literature we know that there are some freshwater tardigrades like Hypsibius dujardini and Dactylobiotus dispar that should be present in ponds.
Our search will not be as easy as with the moss tardigrades.
The situation reminds us a little bit of those websites where the text is virtually undecipherable, perfectly tarnished by a complicated background. In a very similar manner our aquatic tardigrades are hidden within the complicated water lily background pattern.
But searching will be fun as we will come across other fascinating organisms like the rotifer Stephanoceros fimbriatus:

Rotifer Stephanoceros fimbriatus from a sea lily leaf. The five hairy arms form a cage which can be opened and closed - you will understand that Stephanoceros is by no means a vegatarian but a rather brute predator.
Image width 0.5 mm.

Numerous water fleas with are crossing driven by an apparently unending source of energy.

Water flea on water lily leaf (1).

Water flea on water lily leaf (2).

In spite of the romantic colours mother nature can be very cruel. In particular those water fleas are an easy prey for stronger organisms.

Hydra on the unterside of a water lily leaf, devouring a water flea.
In the next issue we will learn how the water bears can indirectly take profit from water flea remains.

Finally, after a long search we have found our first Dactylobiotus dispar tardigrade on the leaf underside. Normally we would have missed it because of its ghost like, faint appearance but we were lucky in so far as the stomach content did provide some contrast. As always in life, once you have seen one you will find the others easily.

Tardigrade Dactylobiotus dispar,
walking on a water lily leaf. Body length ca. 400 µm.

Now you will possibly ask how this faint ghost can be identified as Dactylobiotus dispar. This will be discussed in our next issue, in December. See you.

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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