Re: rotifers, vorticella and unicellular algae feeders

I did some research last night from a book on live foods
for aquariums and found some answers to a few questions.

> Questions:
> How big are rotifers and vorticella in microns?

There are a tremendous variety of these organisms; rotifers is
a phylum (class?) so there are probably thousands of species. 
They are probably not as diverse as bacteria however. They
are higher level organisms than single cell organisms and
feed on protozoa or water borne algae or any organic particles
which they can capture. They are easily visible under low
power with a microscope and the largest should be visible as
specks to the naked eye. They are smaller than hydra.

> Are there other critters which attach themselves to plant
> or other surfaces which might perform a similar function?
> What's the physiology of these things? How do they feed and
> reproduce?

Rotifers come in a variety of shapes but share a physical
characteristic which is used to give them their name. Rotifer
refers to wheel like appendages which have cilia which seem
to rotate as they sweep particles into their mouth orifice.

They are extremely widespread but I believe each type of
rotifer is adapted to a specialized environment. A rotifer
found wild in the temperate zones probably cannot adapt to
life in the tropical environment of a heated aquarium however
a tropical rotifer (say from the Amazon) might be more suited.

The book mentioned reproduction by eggs and that they were
capable of producing different types of eggs according to
seasonal temperature changes similar to daphnia.

I believe vorticella are somewhat smaller in general than
rotifers and have a simpler anatomy than rotifers judging
from the few pictures I looked at. They also had cilia which
appeared primarily to be for locomotion.

The book didn't mention if they were capable of dehydrating
and reviving later similar to other protozoa but it wouldn't
surprise me.

Rotifers are generally classified according to their
method of movement: free swimming, crawling, hopping or attached
although many are not constrained to that single mode. I
believe that rotifers especially those which prefered to
stay close to plant surfaces and hiding places could
survive easily in an aquarium with fish where the larger
free swimming daphnia cannot.

> How do they compare with creatures like freshwater hydra?

Much smaller and they use cilia, not stinging tentacles.

> Where do they come from? Could they be found in natural soils?

They can be found in virtually any puddle of water especially
on aquatic plants. They have specialized habitats such as on
floating plants or detritus etc. I don't think they are
found in terrestrial soil except possibly in a dormant form.
I think you'd have to innoculate your aquarium to get them
although plants you buy probably carry them.

> If we wanted to populate an aquarium with such creatures, what's
> the best way to do it?

I don't think I'd advise collecting wild local rotifers or other
protozoa and adding them to a carefully established planted
aquarium due to the high probability of introducing unwanted
strains of filamentous algaes, or other undesirable organisms
such as nematodes, insect eggs or larvae, amoebae or hydrae.
In fact, local rotifers might not thrive in the warmer tropical
environment. It might be better to get the specialized Amazon
critters which we suppose might have been carefully cultured
and screened for their suitability as rapid reproducers and
consumers of unicellular algae.

> Are these creatures the same ones refered to in German aquarium
> literature as the beneficial creatures which grow on plants
> and which provide a natural food for fishes? (what's the name
> of that stuff?)

Couldn't find the name but I think they're the same thing.

> Can these type of creatures enter a dormant or encysted state
> similar to other microscopic creatures (paramecium?)
> Shouldn't these things already be growing in a healthy, 
> balanced aquarium? What would kill them off?

I think we would find them in aquaria. I imagine snails and
suckermouth catfish feed on them but I suppose they do not
entirely eradicate them. I would think that bleach treatment
or other methods of disinfecting plants would probably kill
any populations currently on plants being added to a sterile

> Could somebody package up these dormant micro-fauna or
> something similar, sell it with a catchy name like
> "Magic Amazon Extract" for the purposes of enhancing your
> aquarium environment and controlling green algae?

It should be easy to find out.

> Do you suppose if somebody got some of this "Magic Amazon Extract" 
> and put it into a sterile nutrient solution, then they could see 
> if it could be cultured, put under a microscope and identified?

They are probably best cultured in a relatively clean culture
of unicellular algae which can be fed mineral nutrients. It's
probably not wise to try to culture them in infusoria since it
would be very difficult to distinguish one microscopic critter
from another.

It's also quite possible that the extract does not contain a
single species but is a random sample of an uncontrolled mixture
of beasties. Since the producer has not volunteered any information
on the nature of this stuff, we can only guess based upon what
other types of products and facilities they are known to possess.

If I were a consumer of such a product, I should really like to
know what specialized facilities the producer had to ensure
quality control. DUPLA, TROPICA, take heed!!

> Do you suppose if some of us had some good cultures of these
> friendly little bugs growing, we could share them all
> amoungst ourselves? (sort of a Poor Man's Magic Amazon Extract)

I suppose we could trade colonies of mixed assorted critters
amoung ourselves on plants or with water samples. We probably
don't know enough without a lot of lab experimentation and
study about how to culture just the single critter in the
Amazon Extract to large populations or to induce it to produce
eggs. Herein may lie the trade secret of the product.