What Does It Mean To Say One Ciliate Eats Another

[DonSchaeffer]

I have seen one protist "eat" another--but mostly on well produced videos. In my own work with microbes, usually microbes are in a biofilm, I can't say I have ever seen any kind of hunt and capture. Usually what I see is microbes soaked in biofilm. It looks like all the microbes are benefitting from the biofilm which itself supplies the nutrition. I typically don't see nutrition as an active solitary pursuit. Organic matter dissolved in biofilm provides the nutrients which are absorbed by microbes moving through it. Question: Is "hunting" and "capture" relatively rare among microbes?

[bkt]

Hi,

Only bigger organisms have the ability to hunt? But some smaller seem to move a lot around on a slide...

I've seen several but rare videos on YT, of amoebas, hydras or other small organisms eating others, or of small protozoan sucking out plant cells contents.

One of those videos showing an hydra not being hungry, ignoring a prey stucked on its tentacles...

I believe this need hours of observations before catching such a scene on a slide.

This being an example, but of bigger organisms:



Another example. I believe it takes days of observations to catch such scenes:

[DonSchaeffer]

Beautiful shots. I rarely observe such integrated behavior. I am working almost entirely with protists in a jar of stagnant water--not from a natural source. It appears that may be a real variable. Almost inevitably--I think--I see protists in a group feeding on bacterial life or products of degeneration of dead organisms. Do you think this is correct?

[bkt]

I am working almost entirely with protists in a jar of stagnant water--not from a natural source.

In a jar, you may be limited by what survived and growed in there. I once had a lot of hydras in my jar, but they seem all gone since months...

You may perhaps buy some cheap plants or moss in any aquarium shop. They should come to you with a lot and diverse residents.

As an alternative, you could get some plants or algae samples from ponds around you. Then days and weeks later, see what you brought to home, to your jar. This technique being prohibited in some areas, were ponds are protected.

[DonSchaeffer]

Thanks. Spring is just starting here in Winnipeg. We are getting the first days above freezing. My samples have all formed indoors. Now I can probably gather a bit more variety.

[Bruce Taylor]

Don, the kind of micro-habitat you've been exploring is sometimes called an "infusion": a natural water sample, rich in decaying matter, kept indoors and occasionally replenished with nutrients (the old-fashioned term "infusoria" is derived from this). This kind of environment tends to favour primary decomposers-- bacteria and fungi--and the organisms that feed on them. So, the large protists you'll encounter will mostly be bacteria-eaters and critters that consume decomposing tissues and organic detritus (bacterivores, fungivores, detritovores, histophages...also, osmotrophs that absorb dissolved nutrients across the cell membrane, rather than gobbling up chunks of matter).

If you want to see large things swallowing each other you are likely to have more luck with fresh samples from relatively clean ponds, lakes and mosses. Try to examine these soon after bringing them home, before they begin to degenerate into desktop infusions.

There are groups of ciliates made up largely of "hunters", adapted to consuming large prey. The class Litostomatea includes many ciliates that have toxicysts for disabling their prey (poison darts, essentially!), and the ability to swallow large creatures. Only a few litostomateans are likely to appear in stagnant, bacteria-rich water (Lacrymaria is one), so it is not surprising that you haven't seen that kind of action very often.

That said, you will sometimes encounter predators in infusorial conditions. The ciliates in the following two videos had been kept in a small aquarium for several months:

Climacostomum swallows a flatworm: https://www.youtube.com/watch?v=DeSk9AQSomQ

Cannibal Climacostomum: https://www.youtube.com/watch?v=2frwxlzsPac

[DonSchaeffer]

Thanks very much, Bruce Taylor. You confirmed my beliefs formed by my experience. Winnipeg is not a great place to find life in a natural state. It's quite cold here 7 months of the year. What you did is clear that up for me. I now have understanding. Thanks.

I am finding some interesting perspectives on the theme of life in a jar.

[DickensRyan]

Phagocytosis is a remarkable phenomenon, as it reflects a complex mechanism of interaction between organisms that plays a pivotal role in sustaining biological systems. This process enables one organism to engulf another for the purpose of obtaining essential nutrients, opening wide avenues for further research in biology and medicine.

[bkt]

Hum... my "jar" is a huge 5L jar with illumination, a lot of plants inside, and a little 10W heater for constant 25°C

Maybe not the best as seasons are gone in there

[charlie g]

Please, don, please do not hold to idea that all life ( protists, meiofauna, and our scale: megafauna) do not go on all seasons..yes even under the ice ( as I often cheer about). Where you reside the ecology thrives in winter.

Think of the neighbors of yours whom enjoy winter: 'ice fishing'...organisms feeding on, swallowing prey organisms...this same nutritional interplay goes on with the smaller protists and meiofauna..all year long.

Organize your microscopy world views..primary producers ( make proteins ,make 'flesh', make protoplasm with sunlight+minerals + some organic substances)...often plants and algae ( the algae blur with protists whom eat algae).

Then the second level..those which eat the plants ( herbivores). Then at third level..those which eat the plant eaters (primary carnivores). Then larger protists and meiofauna which eat the primary carnivores.

Don it's a layer cake of : trophic levels of nutrition...and of course we always have the recyclers to reprocess materials into the vibrant/ richly interacting trophic levels/ layer cake of a community.

Life is so robust and interacting..that we blur the roles, we blur the trophic layers of whom is really eatting whom..the ectoparasites, the endoparasites, the blood feeding insects, the internal bacteria and protozoa which 'feed their hosts'...

termites can not digest the wood products they 'feed upon'..their gut protists digest the wood products..to feed the host termites...complex interplays go on and on year round..your winter time microscopy can be rewarding in Winnipeg, don.

charlie g/ finger lakes/US

[DonSchaeffer]

Thanks Charlie. I am in my 80s, been around for a while. I have been playing with microscopes for more than 20 years. I appreciate intensely what you say and appreciate your insights. Only this year did I discover that the organisms in my glass jars may not be typical of protists in nature. Getting out into places with good natural biomes is not easy for me in my reality--living in a suburb with no natural water sources within easy availability. Winnipeg has a cold climate. Our above freezing natural water is rare here. I will keep plugging though to see if I can get better samples.
.
I will say that in some seasons I get a lot of amebae and larger micro-animals. I will go at it as the weather warms up. I bet I will get some carnivorous creatures this Spring and Summer. Thanks for looking.

[bkt]

Hum...

> please do not hold to idea that all life ( protists, meiofauna, and our scale: megafauna) do not go on all seasons..

> I will say that in some seasons I get a lot of amebae and larger micro-animals

I do not know exactly what is going on in my jar. But it is factual, as I have day illumination and constant heating at 25° (goes above in hot summer time), I've no more seasons in there.

It is running since two years. At some point, hydras appeared, a lot; they seem all gone; lack of nutriments (preys)? I do not know if some will later grow again... some of them may have produced eggs, depending of what my water conditions were. Or do they form eggs according to seasons, and worse conditions?

My water conditions were for some periods bad. I think I've lost the hydras when my bubbling system (for agitation, to eliminate the biofilm) stopped to work, went blocked, and I didn't solve that but late only. This could have caused a lack of oxygen (the minimal air exchange at the surface).

But over that same period, I saw a little snail appeared... from an egg?

I noticed also different sorts of worms in there. But I've seen none since a while. Not sure I still have vorticellas.

At some point, this summer, I'll add algae samples from outside ponds or lakes, hoping I'll get so again more diversity in there....

[DonSchaeffer]

Seems like you have a great system for observation. You must take it very seriously. I don't really have a setting for elaborate collection. In the past I did see a wider variety than I do now--it may be that my stagnant water sample has to be renewed. Now Spring has finally arrived in Winnipeg. In the last couple of days I did collect small new samples from nearby puddles. At my age under current conditions my collection adventures are limited. It's ok though. I find new things every day, both microbes and ordinary weeds and plants. I enjoy reading about the discoveries of my co-adventurers.

[bkt]

My setup is "low tech", see on Youtube, how "low tech aquariums" or "Walstad style aquarium" work.

Filter less aquariums, filters being the costly parts of nowadays sold aquariums. No fertilizers either. Just let things go.

Instead of filtering, fit some plants and algaes in the jar, with some ground for them. They'll do the job. Residents will come in with the plants and samples you add so.

Use any big jar or fish bowl of some 3 to 5L. For a "nano low tech aquarium". Put stuff in there. As Charlie added, microcosm will adapt and grow in it.

I added the bubble system for agitation and for better air exchange at the surface. The top of my jar being very small.

Plus a cheap 10W heater, correct for 5L. And a small 3W led illumination on a timer, for the plants. That way, it is less sensitive to room/home/illumination conditions.

The minimum probably being some illumination, for plants and algaes. Close to a window could do the job, if the jar cannot over heat there due to direct sun exposure.

Who can, will use rain water to compensate evaporation. I use tap water, letting it settle 24h for chlorine to evacuate before adding it to the jar.

Do not add fishes or shrimps inside, you will end disappointed, they'll die in there.


A video about this. Just any big cheap jar or bowl. If plants are well, the micro organisms shall be also. And it won't cost a lot:

[bkt]

A picture of my 5L "jar" or indoor pond. I have to clean a bit things in there. But who cares?

That "grass" shall need CO2, a costly setup. I have none. It has just grown around.

The minimum probably being some acceptable illumination for plants to grow.

[DonSchaeffer]

It's wonderful to be part of a community that plays with nature. I feel so good to be part of a curious bunch of people. I will say I have had some much more diverse biomes in past years. I have been doing this for a a long time. I recently moved to a different neighborhood in Winnipeg. I had to start again and may be working under changed conditions. But it is more fun than a barrel of monkeys.

[DonSchaeffer]

If many ciliates are getting nutrition from just absorbing protein from the medium--the biofilm, why do they have to move around?

[Bruce Taylor]

If many ciliates are getting nutrition from just absorbing protein from the medium--the biofilm, why do they have to move around?

Nearly all ciliates get their nutrients by ingesting smaller organisms (phagocytosis), though some combine this with other strategies (like borrowing nutrients from endosymbiotic algae, i.e. mixotrophy). There is one group of mouthless ciliates call astomes or astomatids which feed by osmotrophy, taking in nutrients through their membranes. However, these nearly always live in the guts of animals, such as worms. They take advantage of their host's digestive processes, absorbing dissolved nutrients in the same way as the host animal's own intestines do.

Osmotrophy does occur in other protist groups, but often in combination with other ways of getting food. Some photosynthetic flagellates, such as Euglena gracilis, live mainly by photoautrophy (eating light!) but are also capable of absorbing dissolved nutrients from the water around them. Most amoebae are capable of phagocytosis (eating large chunks of matter), but some can also "drink" nutrients through a process called pinocytosis, taking in fluids and solutes through little folds and pockets in their membranes.

Being able to move is generally useful to creatures that forage, whether they are browsing on bacteria or stalking larger prey. If food is scarce in one spot, they just move on to another, like cows in a field. Sometimes, you'll see ciliates swooping through dense clouds of bacteria like tiny whales scooping up krill. Some ciliates that feed on tissues are attracted to a fresh corpse by chemotaxis, sensing their way along a chemical gradient until they find what they're looking for (and when they do, they gorge!). When not actually eating, they roam about trying to catch a whiff of death--rather like carrion flies, I suppose.

These are only a few protistan feeding strategies. Describing them all would take a book (or a library full of books!).

[Free2Fish]

Hey Don, although I live south of you I suspect we share a number of season related problems.
I’ve had a fairly successful winter of viewing by increasing the number of specimen jars, feeding them different foods and adding different plant species. Although species numbers settled down I was usually able to find something different by going to different jars or different collection sites within the jars. They’ll be emptied soon and new ones started.

[DonSchaeffer]

I love your photos. Your practice is probably much like mine. A year ago I had to move because my friends with whom I live decided to move to a better apartment. I am just rebuilding my life on a slightly smaller scale. I used to rent a larger basement space but had to move to a smaller (but nicer) basement space. I changed everything when I moved and reduced my stagnant water samples. I am now living like a civilized man with all the plusses and minuses. Civilized men are less like children you know. We don't play as well.

[Free2Fish]

Thanks. Thoughtful thread, I learned a lot. Keep those questions coming, you make interesting queries.

Harry

[DonSchaeffer]

Tip of the hat, Colleague.