Euplotes rejects a potential food item

billporter1456 · Post by **billporter1456** » Mon Feb 29, 2016 6:30 pm

Here we see a protist, Euplotes I believe, capture a food item only to later reject it. Does it have the ability to “taste” the item? Is some form of chemical sensitivity involved?

https://www.youtube.com/watch?v=St8ClIDD7W0[/url]

tsavorite · Post by **tsavorite** » Mon Feb 29, 2016 10:00 pm

Very interesting video.

tsavorite · Post by **tsavorite** » Mon Feb 29, 2016 10:01 pm

Very good timing to capture that sequence.

Sumguy01 · Post by **Sumguy01** » Mon Feb 29, 2016 11:44 pm

Interesting vid.
Thanks for sharing.

Protos · Post by **Protos** » Tue Mar 01, 2016 3:09 am

Bill again you are amazing: filming at the right time !
I would suspect that the cytopharynx membranelles did not do their job. I soubt that "taste" plays a role once in the "mouth"

billporter1456 · Post by **billporter1456** » Tue Mar 01, 2016 5:45 am

Protos wrote:Bill again you are amazing: filming at the right time !
I would suspect that the cytopharynx membranelles did not do their job. I soubt that "taste" plays a role once in the "mouth"

Thanks, Phil! The reason I brought up the "taste" idea is that I had run across this comment about Euplotes, "The selection, rejection, and engulfment process appears to be quite complex and must involve some sort of sensory apparatus lining the buccal cavity." I don't know much about the source of the comment (here's a link: https://www.ebiomedia.com/walking-with-euplotes.html The question of how and whether ciliates select their food is something I'd like to read up on.

As I learn a bit about protists, their sensory capabilities really impresses me. They can be sensitive to light, vibration, temperature, O2 level, and surely other stimuli. And all of this with none of specialized sensory cells that we possess.

carlos.uruguay · Post by **carlos.uruguay** » Tue Mar 01, 2016 6:29 am

Nice video.
Euplotes has a complex neuromotor system, probably not only linked to the movement:
http://www.biolbull.org/content/64/1/53.full.pdf
That is not only exclusive of Euplotes.
Commonly we reduce everything to physical chemical processes.
We know little or nothing of the "conscience" or "way to feel" of all "not humans" living beings.
Perhaps the perception of the reality of living organisms is more complex

Bruce Taylor · Post by **Bruce Taylor** » Tue Mar 01, 2016 6:31 am

Great record of an ordinary but poorly understood behaviour.

There's a smallish body of literature on ciliate food selection & preference. Some work has focused on how food is selected by particle size, "as a function of the morphological properties of the mouth apparatus" (Fenchel, 1980) Fenchel had the clever idea of using latex microbeads to test size selection, and his results showed that each species had a "size spectrum" for ingested particles. A similar study of Euplotes mutabilis showed the same phenomenon and got really specific about the size of microbead that species liked best (Wilks, 1998).

Other researchers have shown that ciliates have some (probably chemosensory) ability to discriminate between diatoms of similar size (Hamels et al, 2004), and that some critters do show preference for certain bacterial prey...even distinguishing between different
physiological states of the same prey (Ayo et al, 2008).

Since some ciliates have pretty good chemotaxis (I've recorded video of scavenger species homing in on a dead crustacean), it's reasonable to suppose that they can identify and reject distasteful food when it hits the buccal cavity.

Bruce Taylor · Post by **Bruce Taylor** » Tue Mar 01, 2016 6:34 am

carlos.uruguay wrote:Nice video.
Euplotes has a complex neuromotor system, probably not only linked to the movement:
http://www.biolbull.org/content/64/1/53.full.pdf
That is not only exclusive of Euplotes.
Commonly we reduce everything to physical chemical processes.
We know little or nothing of the "conscience" or "way to feel" of all "not humans" living beings.
Perhaps the perception of the reality of living organisms is more complex

Carlos, the research on the ciliate "neuromotorium" was discredited a long time ago. I wrote a little blog post about "The Rise and Fall of the Ciliate Cytobrain", a while ago: http://www.itcamefromthepond.com/2013/1 ... cytobrain/

That's not to say that ciliates don't sense their environment. They do! They can have tactile awareness, photosensitivity, chemical sensing, and even gravitational taxis (some of them know which way is up!). However, there's no particular reason that this should require a cellular analogue to the animal nervous system.

carlos.uruguay · Post by **carlos.uruguay** » Tue Mar 01, 2016 6:42 am

Bruce Taylor wrote: Carlos, the research on the ciliate "neuromotorium" was discredited a long time ago. I wrote a little blog post about "The Rise and Fall of the Ciliate Cytobrain", a while ago: http://www.itcamefromthepond.com/2013/1 ... cytobrain/
That's not to say that ciliates don't sense their environment. They do, in many different ways. However, there's no particular reason that this should require a cellular analogue to the animal nervous system.

Thank you very much Bruce !!
and apologies to the rest of the forum members for my incorrect information!

Bruce Taylor · Post by **Bruce Taylor** » Tue Mar 01, 2016 6:56 am

carlos.uruguay wrote: What is currently known about the ciliates "perception"?

I was editing my previous post as you were writing. As I mentioned, we know that ciliates can sense their environment in many ways...through specialized tactile cilia, light-sensing pigments in the cortex, gravity-sensing bodies (in Loxodes, for example). And, like other microbes (both eukaryotic and prokaryotic) they show a wide range of chemotactic behaviours.

However, sensory input does not need to travel up through a hierarchy of "nerves" toward a centralized "information interpreter" or "executive organelle" (i.e. there's no need to think they have anything like a "cytobrain"). The "neuromotorium" research arose from simple zoocentric prejudice, I think...we have trouble imagining that "intelligence" can be distributed, and not centralized (that was the subject of another blog post: http://www.itcamefromthepond.com/2013/11/23/156/ )

Cactusdave · Post by **Cactusdave** » Tue Mar 01, 2016 7:14 am

Very anthropomorphic I know, but I wonder if there is any kind of satiety mechanism? This Euplotes looks kind of 'full' with a mass of what appears to be undigested and partly digested food items in its food vacuoles. Could it be that it just wasn't possible to create a new food vacuole for this largish prey item?

billporter1456 · Post by **billporter1456** » Tue Mar 01, 2016 7:16 am

carlos.uruguay wrote:Nice video.
Euplotes has a complex neuromotor system, probably not only linked to the movement:
http://www.biolbull.org/content/64/1/53.full.pdf
That is not only exclusive of Euplotes.
Commonly we reduce everything to physical chemical processes.
We know little or nothing of the "conscience" or "way to feel" of all "not humans" living beings.
Perhaps the perception of the reality of living organisms is more complex

Thanks for the link, Carlos! That's an interesting article and it led me to an article about the life of one of the researchers (Taylor) that I found interesting as well: http://www.nasonline.org/publications/b ... rles-v.pdf

billporter1456 · Post by **billporter1456** » Tue Mar 01, 2016 7:25 am

Cactusdave wrote:Very anthropomorphic I know, but I wonder if there is any kind of satiety mechanism? This Euplotes looks kind of 'full' with a mass of what appears to be undigested and partly digested food items in its food vacuoles. Could it be that it just wasn't possible to create a new food vacuole for this largish prey item?

An interesting speculation, Dave. After all, the pellicle in Euplotes seems pretty rigid, so there is a clear limit to how much the cell can ingest. Maybe that's the answer because I believe Euplotes are known to consume Euglenids.