Question About Invert Waste

[Joe Tony]

Hello, this isn't a tip regarding tank care so much as a scientific inquiry. It's generally accepted that inverts ie snails, clams, sea urchins, starfish, shrimp, crabs, etc. don't produce waste, or rather produce very minimal waste compared to fish, but scientifically I never understood why that was. Inverts tend to eat a lot, being that they're scavengers or ravenous algae eaters, and I always understood animals that eat a lot to need a lot of energy and therefore produce a lot of waste. Yet invertebrates in an aquarium don't produce much waste, despite having a strong apetite. So where does all of that food go? Does it contribute to molting in the case of crustaceans? Do they grow faster? Is most of the waste a gaseous form? Or does the nitrate/bioload people talk about come from fish pee, and that invertebrates don't pee, but only poop?

Can someone explain the science surrounding it? What happens with the energy that invertebrates utilize from the food they eat, since most of it isn't expelled as a waste product?

 

[lapin]

Interesting thought.
Un scientific response:
My take is that inverts and worms digest as much as they can whats left is converted to small enough particles that bacteria can process the rest.

 

[Joe Tony]

Interesting thought.
Un scientific response:
My take is that inverts and worms digest as much as they can whats left is converted to small enough particles that bacteria can process the rest.

But wouldn't the bacteria that consume the tiniest particles still convert the ammonia to nitrite, and then from nitrite to nitrate, and thus there would still be a significant amount of nitrate in the tank? Unless you're talking about the nitrogen gas producing bacteria, but I thought that didn't exist in most systems.

 

[Vette67]

The smaller inverts, I’m not sure about. But what I can say is that urchins produce a lot of waste. I can see them pooping a lot. Is it some lower, more consumed form of waste, I cannot say. It is definitely much more visible than my other inverts.

 

[Joe Tony]

The smaller inverts, I’m not sure about. But what I can say is that urchins produce a lot of waste. I can see them pooping a lot. Is it some lower, more consumed form of waste, I cannot say. It is definitely much more visible than my other inverts.

So if you have a sea urchin and you want it to deal with the algae you have in the tank, do you have to remove a lot of that poop, in order to prevent it from feeding the algae growth again (unless its coralline algae, in which case you just leave it in there for the coralline to grow back)?

 

[Vette67]

So if you have a sea urchin and you want it to deal with the algae you have in the tank, do you have to remove a lot of that poop, in order to prevent it from feeding the algae growth again (unless its coralline algae, in which case you just leave it in there for the coralline to grow back)?

I have 2 rock urchins in my 180. They predominantly eat coralline. They just move along my sides and back glass, continually munching coralline. I don't know for sure, but I assume what comes out is essentially sand. I don't think the they digest the calcium, but I don't know that for sure. Maybe some of it... I have an oolitic sand bottom, so I don't really clean anything up. I just let it go back into the gravel.