"Tell me, water bear: are you a predator or a vegetarian?"
When looking at the literature you will find out that some tardigrade species,
in particular those with rather big individuals are considered to be carnivorous.
Already in the beginning of the 20th century the German water bear specialist
Prof. Ferdinand Richters complained that it was difficult to study the
feeding behaviour of those tardigrades: "How seldom do we encounter an eating tardigrade !"
What should then be done in order to find out more about a potentially carnivorous
behaviour? There is a very simple answer: as most tardigrades are transparent we just
have to look at the contents of their stomachs. When you are careful you
will be able to study the stomach content without doing any harm to the tardigrade.
Milnesium tardigradum is known to be a predator,
so for the beginning we should watch out for big Milnesium water bears, or,
not quite as good, big Macrobiotus water bears.
Here we will show as an example what we have found out when studying
a big Milnesium tardigrade: