Acropora 'Target Feeding' Response with Particulate Coral Food

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That 'coral food' is much much too large for acropora sp. corals. That looks like something a brain or chalice coral would eat readily though.

For acros and most sps, think bacterial or sub-40 micron in size. Target feeding discourages capture and retention of captured material, even if it is biologically nutritious. In fact, the millepora behavior was almost identical to predation anxiety corals exhibit when parrotfish are nearby.
 
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chcgregg

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That 'coral food' is much much too large for acropora sp. corals. That looks like something a brain or chalice coral would eat readily though.

For acros and most sps, think bacterial or sub-40 micron in size. Target feeding discourages capture and retention of captured material, even if it is biologically nutritious. In fact, the millepora behavior was almost identical to predation anxiety corals exhibit when parrotfish are nearby.

Have a look at the photos I just posted before this.

Direct evidence of capture and ingestion. And that Cyclops was about 1mm long. At least 50x the size of the largest particles in that coral food.
 
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chcgregg

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This is what actual feeding looks like:



I didn't see any ingestion of that coral food in that video, just more zoomed in.........

Corals produce mucus when stressed, or to capture foods. They will then eject the slime, or pull it in along with the captured foods into the mouth of the polyp.

Acropora producing mucus like this is a stress response, not feeding. As soon as the water current returns, the mucus is pushed away by the water, effectively ridding the coral of the irritants.
 

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You can see food consumption as a gentle influx of particles into the polyp. Only a few tiny specks are consumed. That is how acropora eat.
 

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I just did, you posted them as I was still typing (And verifying, my memory ain't what it ever was) my last post.

Forgive me if I am skeptical, but by what mechanism did an acropora polyp actually ingest, then digest, a copepod within three hours.

Please take further observations after this time period to verify the excretion of indigestible and non-nutritious waste products of that polyp as well. I would expect a less efficient digestive system than typical, so will there be a measurable discharge of wastes?
 
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chcgregg

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I just did, you posted them as I was still typing (And verifying, my memory ain't what it ever was) my last post.

Forgive me if I am skeptical, but by what mechanism did an acropora polyp actually ingest, then digest, a copepod within three hours.

Please take further observations after this time period to verify the excretion of indigestible and non-nutritious waste products of that polyp as well. I would expect a less efficient digestive system than typical, so will there be a measurable discharge of wastes?

I'm assuming partial digestion took place, as stated with a few scientific articles researching the effects of Acropora growth (Acropora tenius) and being fed Artemia salina nauplii daily for 5 months.

Against the controls, from a single polyp, the average of the colonys grew 25mm in diameter, where as the controls did not. They also mentioned that the coral ingested, and "digested" the Artemia salina within 2 hours, after then it was ejected into the water column.

But if it isn't digesting it within 2 hours, why did the target fed Acropora tenius grow so much more than the controls?

As I have no possible way of measuring waste products, I am, based on evidence, assuming digestion, and at least partial digestion took place.
 
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I'm assuming partial digestion took place, as stated with a few scientific articles researching the effects of Acropora growth (Acropora tenius) and being fed Artemia salina nauplii daily for 5 months.

Against the controls, from a single polyp, the average of the colonys grew 25mm in diameter, where as the controls did not. They also mentioned that the coral ingested, and "digested" the Artemia salina within 2 hours, after then it was ejected into the water column.

But if it isn't digesting it within 2 hours, why did the target fed Acropora tenius grow so much more than the controls?

The difference in size between nauplii of Artemia Salina and a nearly fully grown cyclops pod as displayed in your photo is the difference between you eating a boiled egg and a basketball.

I would expect the process of digestion to be slower, but by a much greater degree than 33%.

I look forward to seeing the progress of your investigation.
 
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chcgregg

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The difference in size between nauplii of Artemia Salina and a nearly fully grown cyclops pod as displayed in your photo is the difference between you eating a boiled egg and a basketball.

I would expect the process of digestion to be slower, but by a much greater degree than 33%.

I look forward to seeing the progress of your investigation.

A good point you raise, it would be very interesting to conduct experiments to work out how much, if any quantity, of the Cyclops was digested.

Thanks for making me think about this more, I hope to learn more about this process.

But undeniably, the photos show that the Acropora did indeed capture and ingest a rather large source of food.
 
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chcgregg

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Beautiful video. I dont care if they eat or not just please take more video :)

That is a great song as well, gymnopedia I believe it's called. I love when that comes on when I'm working in the fish room.

Thank you very much I will be making more!!

A lot of Erik Satie's music is wonderful, very calming.
 

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I think that Veron once said that if they slime at all, whatever they eat from any caught food will be a net negative in energy. If not him, then my apologies for misremembering who it was. Also, smaller is better because they can digest it "in time" where they might have to spit that whole cyclops back out nearly whole. I have NEVER seen any evidence that the juice is worth the squeeze when feeding acropora - if anybody has anything that shows that the energy to catch and digest is worth it, then I would really like to see it.

If you are going to experiment with acropora, then beware of studies and stuff that deal with "coral" in general... there is a big difference between feeding a dendro or duncan than an acropora.
 
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chcgregg

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I think that Veron once said that if they slime at all, whatever they eat from any caught food will be a net negative in energy. If not him, then my apologies for misremembering who it was. Also, smaller is better because they can digest it "in time" where they might have to spit that whole cyclops back out nearly whole. I have NEVER seen any evidence that the juice is worth the squeeze when feeding acropora - if anybody has anything that shows that the energy to catch and digest is worth it, then I would really like to see it.

If you are going to experiment with acropora, then beware of studies and stuff that deal with "coral" in general... there is a big difference between feeding a dendro or duncan than an acropora.

Thanks for your input! I will send you some studies through PM which are interesting, but these are conducted with Artemia salina, not Cyclops. But you are right, it may not be worth the energy to attempt digestion of a larger potential food source, as the yes, the net energy expenditure will be greater than gained. I was just surprised to see the Acropora tenius ingest the Cyclops, being such a big (relative) food source.

And mucus, if it can't be consumed afterward, is a waste of energy if excreted into the water column. I like to think of it this way. Why would such a coral very quickly produce mucus when target fed particulate foods (being a quicker mechanism generally requires a lot more energy) and eject that mucus, and pull in it's polyps if it didnt actually ingest any, even though it may be reasonably nutritious?

Definitely a stress response. I have tried other foods which don't evoke such a vigorous mucus production, and may be captured, but I will need a closer sense and less water flow to see clearer.
 

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I read a study out of Australia about a year ago regarding acropora and feeding but cant find it now. If I remember correctly, there was no increase in growth. I'll keep looking.
 

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I have seen the "study" with brine shrimp and Poci or Stlyo (forgot which). I don't really care about this one since these are not acropora. It is easy to get these to catch food... no idea if they get anything out of it...
 
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chcgregg

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I have seen the "study" with brine shrimp and Poci or Stlyo (forgot which). I don't really care about this one since these are not acropora. It is easy to get these to catch food... no idea if they get anything out of it...

The study I am referring to involves Acropora tenius. And another study involves Acropora millepora.
 
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chcgregg

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After chcgregg's videos I still am left questioning if feeding is required/desired.

Do keep in mind that this in reference to the food by Ocean Nutrition. It also depends on density of the particulate matter, and composition. Other foods might be more desirable.
 

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There is absolutely no evidence that it is required for acropora and many other corals outside of NPS. Desired is a different question of which I have never seen a good answer. All of my experience has grown many tanks wall-to-wall with acropora (to where you have to start over) without me feeding anything - no idea if the corals catch food in some other way.

What always amazes me when this topic comes up is that people are so concerned with "feeding" their corals, yet they could get much more mileage out of their lights. So many people run cut-spectrum and low wattage lighting and either forgot, or never understood, that this is what generates the true food (through the zoox). You get arguments like "it is enough" or "just fine" with the lighting choices, but with using a "coral food" or other "supplement" people are looking for the ultimate. Why the difference?

Post up those studies... all would probably like to see.
 
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chcgregg

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There is absolutely no evidence that it is required for acropora and many other corals outside of NPS. Desired is a different question of which I have never seen a good answer. All of my experience has grown many tanks wall-to-wall with acropora (to where you have to start over) without me feeding anything - no idea if the corals catch food in some other way.

What always amazes me when this topic comes up is that people are so concerned with "feeding" their corals, yet they could get much more mileage out of their lights. So many people run cut-spectrum and low wattage lighting and either forgot, or never understood, that this is what generates the true food (through the zoox). You get arguments like "it is enough" or "just fine" with the lighting choices, but with using a "coral food" or other "supplement" people are looking for the ultimate. Why the difference?

Post up those studies... all would probably like to see.

That's right!! I will post the links up, I am just at work at the moment so will find a spare moment to search them on my phone at lunch.
 

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