Sixty’s equation - feather sea star observations

[sixty_reefer]

PLEASE DO NOT ATTEMPT TO REPLICATE THIS IN AT HOME...

Im opening this thread as I’d like share some development that may become useful in future in the research to keep this organism alive and healthy in home aquaria.

So we’re to start really.

Probably the most common question is feeding, is the animal eating enough?

For feeding I’ve used a equation that no one else seems to understand, I’ve tried to explain it before several times but the discussion doesn’t seem to make sense to anyone else. I’ve applied the basics to a new tank and the results were a build up of floating biofilms full of bacteria, single cell zooplankton and organic matter.

Another positive that I’ve observed with this implementation is a fairly stable tank

No3 is kept at a stable 5 mg/l , phosphate is currently at 0.2 mg/l with a ph of 8.2

This is how they look under the microscope.



This is how the floating biofilms looked in the tank prior to the introduction of the specimen.



It’s to early in the process to determine anything although I’ve been also examining the waste from this Crinoid that usually happens 2 to 3 times a day.

This is how the Crinoid waste looks like under the microscope.



And in the tank

It seems with this particular specimen the waste is moved out the same way the food is collected, it sends it out through the feathers and stays around him until it eventually scatters around the tank, with my limited knowledge observing it under the microscope, it seems that the particle size it’s bigger than anything added to the tank it also seems that there is no bacteria or single cell zooplankton around the waste making me believe that the Crinoid possibly digested the organic matter and the microbes attached to it.

Since the introduction of this Crinoid the protein skimmer collection cup has also started to collect the waste fairly effectively going from a slightly yellow to a dark brown consistency (pic below)

Not all observations are positive

Since the introduction of this specimen to the tank it has lost a few feathers, 6 to be more precise, it happened a few days after it was introduced and I can’t tell if it was damaged wile transporting to the house or if it was stressed related.
Since then it has been regrowing 4 feathers that are at different stages of development, below is a picture with the two less developed growing in the same area as the previous ones were lost.

The previous day to the feathers being lost, he also lost his cirri, that is now also regrowing 3 new legs.

It’s been a stressful couple weeks as a one point it seemed that all had failed before it even had started, I don’t know how long the star has been in captivity but for now it seems that there is a small possibility that it is feeding on something and that the parts lost via transport or stress from changing environment may be regained.

I’ll finish the introduction with a video of the star catching some of the floating biofilms and will update once I can get some more information.

​

 

[MarineandReef Jaron]

Thanks for all of the info. These are some of the most beautiful invertebrates in the ocean and I have never had success keeping them. I would love to learn more. I recently ordered a Caribbean basket SeaStar in hopes it would be easier than a true crinoid, but it arrived completely melted.

 

[sixty_reefer]

Thanks for all of the info. These are some of the most beautiful invertebrates in the ocean and I have never had success keeping them. I would love to learn more. I recently ordered a Caribbean basket SeaStar in hopes it would be easier than a true crinoid, but it arrived completely melted.

Hi have read of other folks having more success with basket stars also.
It’s early in my journey to comment much about it, I’ve gathered feeding although I’m also noticing how sensitive they are, I was moving it with a turkey blaster gently every now and then to clean the tank but I had to stop as anything touching it, he doesn’t react well to it.

 

[livinlifeinBKK]

I love the approach you're taking (making very close observations as frequently as possible and using what you observe to guide your next move)!
I feel one of the biggest obstacles to keeping crinoids lies partially in the fact that they're very difficult to identify at the species level and the nutritional requirements almost certainly vary to some extent by species. Out of the hundreds of species identified, I think only several have had gut and fecal contents identified in an attempt to determine diet and the results of at least a few of those studied revealed that contents varied even in the same species. I distinctly recall reading that although they may accept a variety of particulate matter, much of it isnt digested...the reason being that they rely on the currents to deliver their food (it was also discovered that gut contents varied by season for the same reason). If particles are a diameter which fall into the correct range to be transported down the ambulacral groove, theyll generally be taken into the stomach and finally excreted from the anus...whether the food contributes much or at all to nutrition is difficult to say without analysis. Like most echinoderms, they can use DOC to supplement their diets which may be very important for at least some species...since you mentioned it has lost arms, maybe try to increase the DOC in the tank since gaining nutrition from passive uptake would likely expend less energy? Just a thought.

 

[sixty_reefer]

I love the approach you're taking (making very close observations as frequently as possible and using what you observe to guide your next move)!
I feel one of the biggest obstacles to keeping crinoids lies partially in the fact that they're very difficult to identify at the species level and the nutritional requirements almost certainly vary to some extent by species. Out of the hundreds of species identified, I think only several have had gut and fecal contents identified in an attempt to determine diet and the results of at least a few of those studied revealed that contents varied even in the same species. I distinctly recall reading that although they may accept a variety of particulate matter, much of it isnt digested...the reason being that they rely on the currents to deliver their food (it was also discovered that gut contents varied by season for the same reason). If particles are a diameter which fall into the correct range to be transported down the ambulacral groove, theyll generally be taken into the stomach and finally excreted from the anus...whether the food contributes much or at all to nutrition is difficult to say without analysis. Like most echinoderms, they can use DOC to supplement their diets which may be very important for at least some species...since you mentioned it has lost arms, maybe try to increase the DOC in the tank since gaining nutrition from passive uptake would likely expend less energy? Just a thought.

I was trying to look for some articles or data on the subject of their poop but wasn’t able to find much information would be cool if you could share some.
It’s interesting that you mentioned DOC as that’s what I’ve been feeding him so far, because you seem to understand the importance of it I don’t mind discussing what I’m doing with you. It sounds complicated but it is actually fairly easy in practice.

What I believe I’ve done is:

Before the star was introduced, I’ve started adding SLDOC to the tank, that is a particular carbon extracted from macro and micro algae’s, basically it’s powder carbohydrates from macro algae’s.
Once added to the tank they will interfere with nutrient like phosphate an Nitrogen due to bacteria being able to breakdown some of this carbon and assimilate amino acids in the water column (that I’m dosing separately), if amino acids and other forms of early nitrogen are not available this bacteria will start using Nitrate.

My initial goal was to find a balance between aminos and organic carbon so that Nitrate remain stable as I’ve read that this stars are very sensitive to parameter change, one of the goals was to have Nitrates locked at 5 mg/l.

The end result of this experiment was a particular organic carbon that has a bacteria biofilm rich in Nitrigen and some phosphate. That also created a predator for the rich in nutrients bacteria in the form of Protozoa.

Basically it formed a sandwich that has a high amount of C some Nitrogen (in the bacteria and single cell Protozoa) and a little P from the tissue of bacteria and Protozoa.

Image of the life in biofilm in thank AKA sandwich

Image of waste - No microscopic life

What I believe it’s happening it’s that the start is ingesting this films and using this nutrients as most organisms will need in nature.

The waste observed shows the carbon that I’ve been feeding them but I believe the energy has been removed as there is no bacterial movement around it. I would classify the waste as RDOC. (Organic matter without any nutrients)



I call the above sixty’s equation as it shows a direct relation between CNP in saltwater. And the tank is kept balanced at 5mg/l due to that. I’ve found this equation in a conversation with Randy a few years back, tried to discuss it but no one seems to understand it or see it as I do.

I apologise if it’s a bit confusing.

But basically I’m using powder organic carbon to replicate the make up of seawater in certain environments in the wild were this organisms live. The powder organic carbon in the wild I would guess that is made naturally by the decomposition of algae’s and phytoplankton.

In addition I don’t think I’ve mentioned earlier but I’ve keep the tank bear to make the observation a little easier, minimise the chances of him to get hurt and help with the food to stay in suspension on the water column, if I had sand most would of just stay trapped in it.

 

[sixty_reefer]

@Bongo Shrimp wondering if you could join the thread as you have been one of the only persons that I know that had a long successful experience with this.

 

[livinlifeinBKK]

I was trying to look for some articles or data on the subject of their poop but wasn’t able to find much information would be cool if you could share some.
It’s interesting that you mentioned DOC as that’s what I’ve been feeding him so far, because you seem to understand the importance of it I don’t mind discussing what I’m doing with you. It sounds complicated but it is actually fairly easy in practice.

What I believe I’ve done is:

Before the star was introduced, I’ve started adding SLDOC to the tank, that is a particular carbon extracted from macro and micro algae’s, basically it’s powder carbohydrates from macro algae’s.
Once added to the tank they will interfere with nutrient like phosphate an Nitrogen due to bacteria being able to breakdown some of this carbon and assimilate amino acids in the water column (that I’m dosing separately), if amino acids and other forms of early nitrogen are not available this bacteria will start using Nitrate.

My initial goal was to find a balance between aminos and organic carbon so that Nitrate remain stable as I’ve read that this stars are very sensitive to parameter change, one of the goals was to have Nitrates locked at 5 mg/l.

The end result of this experiment was a particular organic carbon that has a bacteria biofilm rich in Nitrigen and some phosphate. That also created a predator for the rich in nutrients bacteria in the form of Protozoa.

Basically it formed a sandwich that has a high amount of C some Nitrogen (in the bacteria and single cell Protozoa) and a little P from the tissue of bacteria and Protozoa.

Image of the life in biofilm in thank AKA sandwich

Image of waste - No microscopic life

What I believe it’s happening it’s that the start is ingesting this films and using this nutrients as most organisms will need in nature.

The waste observed shows the carbon that I’ve been feeding them but I believe the energy has been removed as there is no bacterial movement around it. I would classify the waste as RDOC. (Organic matter without any nutrients)



I call the above sixty’s equation as it shows a direct relation between CNP in saltwater. And the tank is kept balanced at 5mg/l due to that. I’ve found this equation in a conversation with Randy a few years back, tried to discuss it but no one seems to understand it or see it as I do.

I apologise if it’s a bit confusing.

But basically I’m using powder organic carbon to replicate the make up of seawater in certain environments in the wild were this organisms live. The powder organic carbon in the wild I would guess that is made naturally by the decomposition of algae’s and phytoplankton.

In addition I don’t think I’ve mentioned earlier but I’ve keep the tank bear to make the observation a little easier, minimise the chances of him to get hurt and help with the food to stay in suspension on the water column, if I had sand most would of just stay trapped in it.

I actually do understand what you're saying and it sounds like youre thinking on the right track! Most members of Phylum Echinodermata can actually draw in DOC or other nutrients such as amino acids in the case of Asteroids. One study I recall reading through concluded precisely what you mentioned above (you used an acronym, but I think when you said RDOC, the "R" is REFRACTORY). Is that what you meant? If so, that aligns with the research ive read through over time. It wasn't confirmed, but likely thay the species being studied was obtaining at least some nutrition not from the fish fecal matter it consumed (in that study), but from the associated microorganisms.
The really difficult part is that they'll consume particles they derive nothing from just like theyll consume particles which are nutritious for them. That leaves us with the question, what do they really need if theyll accept particulate matter which carries 0 value (literally sand grains of the right size may be ingested).

Does the feather star exhibit a feeding posture at any time?

 

[livinlifeinBKK]

And I can try to find some of the research Ive read for you, but a lot of what Im saying I've learned over a long time from a variety of books, articles, personal communications with those who have studied them professionally, etc. If I can find a couple good research studies I read previously Ill link them for you!

Personally, I dont think feather stars should be in the hobby because they have such a hogh mortality rate and are commonly an impulse buy. However, you're trying to carefully study them and learn about them, which I have no objection to whatsoever.

 

[sixty_reefer]

I actually do understand what you're saying and it sounds like youre thinking on the right track! Most members of Phylum Echinodermata can actually draw in DOC or other nutrients such as amino acids in the case of Asteroids. One study I recall reading through concluded precisely what you mentioned above (you used an acronym, but I think when you said RDOC, the "R" is REFRACTORY). Is that what you meant? If so, that aligns with the research ive read through over time. It wasn't confirmed, but likely thay the species being studied was obtaining at least some nutrition not from the fish fecal matter it consumed (in that study), but from the associated microorganisms.
The really difficult part is that they'll consume particles they derive nothing from just like theyll consume particles which are nutritious for them. That leaves us with the question, what do they really need if theyll accept particulate matter which carries 0 value (literally sand grains of the right size may be ingested).

Does the feather star exhibit a feeding posture at any time?

Yes, I used RDOC in reference to the observation on it’s poop, and SLDOC (semi-labile) to the carbon ingested, my assumption it is that they may be possibly extracting the carbohydrates in their stomach with the help of some sort of enzymes and pooping the left overs that are just RDOC, just a assumption or educated guess if you want to call it that.
The fecal samples that I’ve observed so far, visually resembles grains of sand with a slimy coat on it. I can’t examine what it’s the slimy substance attached to their fecal excrement.

As for feeding I’ve observed a few different reactions, in the beginning I was collecting them in the protein skimmer and using a turkey baster to add some over it’s mouth the reaction is just under.



A few seconds after I’ve sprinkled the food over it there is a full body reaction with all the feathers moving like trying to catch something.

Other observations is wend i agitate the back sump and floor glass pane to release any settled debris and I notice that she opens fully and starts rotations slowly.

Other observations is even wend closed he tends to have 4 feathers open every now and den and create flow to lift particles from the aquarium floor.

The only thing I couldn’t observe as of yet it’s actual ingestion as the mouth is not visible due to have a lot of feathers covering that part of the body.


Another small observation it’s that he seems more active now that once I first got it. He spent the first week in the corner of the aquarium were debris used to collect and now it wonders all over the aquarium, last night I’ve observed it going for it’s first swim since I’ve added him to the tank.

 

[sixty_reefer]

And I can try to find some of the research Ive read for you, but a lot of what Im saying I've learned over a long time from a variety of books, articles, personal communications with those who have studied them professionally, etc. If I can find a couple good research studies I read previously Ill link them for you!

That would be amazing if you can.

Personally, I dont think feather stars should be in the hobby because they have such a hogh mortality rate and are commonly an impulse buy. However, you're trying to carefully study them and learn about them, which I have no objection to whatsoever.

I agree, it wasn’t my first choice initially I was looking for a carnation coral but this species come up before the carnation.

 

[sixty_reefer]

He started doing this for the past few days as I agitated the water to lift the debris from the bottom pane of glass, it seems that any extra water agitation near him may be stressing it out somehow. Will stop doing that and just try and clean the pane gently from here on now.

 

[BristleWormHater]

You are doing a great job! These are so hard I don't think any aquariums even keep these. Beautiful little guy, I hope he does well!

 

[sixty_reefer]

You are doing a great job! These are so hard I don't think any aquariums even keep these. Beautiful little guy, I hope he does well!

I haven’t done much as off yet

I’m spending my evening looking at fecal excretion images and it’s not was fun as I thought it would be.

They make orange poop that as much of a science I can contribute and probably one of the most dirty animal I’ve ever kept

That’s one day worth of poop.

 

[sixty_reefer]

The single cell zooplankton seems to still be in good numbers

 

[sixty_reefer]

This is how “Bob” spends most of its time now

 

[sixty_reefer]

Just after the picture I’ve lifted the debris in the tank. This was the reaction!

 

[sixty_reefer]

Having started this tank only a month ago, I have been testing every two days to ensure the equation hasn’t come out of balance with the additional oxygen monitoring due to microbial enhancement.
If it does come out of balance I just readjust it enough to keep nitrate at 5 mg/l

No3 5 mg/l
Po4 not tested
Ph 8.2
Kh 10
O2 10 mg/l

 

[BeanAnimal]

Hi - why are you not following the research that has already been compiled regarding how these animals feed and what they feed on?

I did you a favor and spent a few hours researching for you. I was able to find more than a dozen relevant resources, a few behind paywalls and a few well cited excerpts.

The primarily food source Is suspended particulate organic matter (POM), specifically phytoplankton not DOC. They don't consume biofilms or dense bacterial aggregates (biofilm sandwiches).

1. Messing, C. G. (1997). "Living Comatulids (Feather Stars) in Deep-Water Habitats." - This study details how crinoids feed
   
   
2. La Touche, R. W., & West, J. (1980). "The Feeding Mechanisms of Antedon bifida (Crinoidea)." Marine Biology, 60(1), 45-52. More study of crinoid feeding
   
   
3. James G. Saulsbury. (2021). "Comatulid Crinoids in a Changing Ocean: Predation, Respiration, and Shifting Centers of Diversity" - Cites information regarding feeding and that phytoplankton make up a bulk of the diet.

There are a dozen more, but that should get you started.

Dissolved organic carbon (DOC) from sources like algae or labile carbon dosing that you keep mentioning and promoting in these threads mainly results in heterotrophic bacterial blooms rather than forming a structured, layered food web. Sure you can grow some zooplankton but if you read the research, you are headed in the wrong direction.

So the "sandwich" idea is creative, but not supported by the research.

 

[sixty_reefer]

Hi - why are you not following the research that has already been compiled regarding how these animals feed and what they feed on?

I did you a favor and spent a few hours researching for you. I was able to find more than a dozen relevant resources, a few behind paywalls and a few well cited excerpts.

The primarily food source Is suspended particulate organic matter (POM), specifically phytoplankton not DOC. They don't consume biofilms or dense bacterial aggregates (biofilm sandwiches).

1. Messing, C. G. (1997). "Living Comatulids (Feather Stars) in Deep-Water Habitats." - This study details how crinoids feed
   
   
2. La Touche, R. W., & West, J. (1980). "The Feeding Mechanisms of Antedon bifida (Crinoidea)." Marine Biology, 60(1), 45-52. More study of crinoid feeding
   
   
3. James G. Saulsbury. (2021). "Comatulid Crinoids in a Changing Ocean: Predation, Respiration, and Shifting Centers of Diversity" - Cites information regarding feeding and that phytoplankton make up a bulk of the diet.

There are a dozen more, but that should get you started.

Dissolved organic carbon (DOC) from sources like algae or labile carbon dosing that you keep mentioning and promoting in these threads mainly results in heterotrophic bacterial blooms rather than forming a structured, layered food web. Sure you can grow some zooplankton but if you read the research, you are headed in the wrong direction.

So the "sandwich" idea is creative, but not supported by the research.

You do realise that eventually we will become good friends

How is it what I’m doing much differently from phytoplankton?

I do not know if it’s going to work and as I’m only now realising that feeding it’s only one of the smallest challenges in keeping this animals, for the first time since I’ve started this hobby I’m actually nervous in performing a water change, that’s how sensitive I’ve read they are.
Having a small volume of water is not helping the outcome of the experiment.

 

[sixty_reefer]

Restocking on N and P

Almost 100ppm of nitrates have been dosed in the last 3 week.

Thank still stable at 5 mg/l​