Live rock critters - captive or wild?

I keep a saltwater fish tank, and was wondering if the numerous little critters that hitchhike into the tank on live rock would count as wild observations or not - they were moved there by humans, but not intentionally. I do know where the rock came from, but not when it was collected. A good deal of critters have ended up in the tank this way, from mantis shrimps, bristleworms, crabs, pistol shrimps, sea cucumbers and urchins.

For those who don’t know what I mean, live rock is marine rock rubble that has been left in the ocean to allow bacteria, algae, and a number of tiny animals to grow on and colonise it. It is used in marine aquariums as both a form of filtration and to create a more natural tank environment.

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I reckon captive. You put them in the tank whether you intended to or not. The grey area would be a species that might have colonised the tank by itself, such as a marine chironomid midge.

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If you know for certain where they came from then I think that it would be proper to treat them as wild but a place of observation would be their origin, not your home. There remains a problem with date which you don’t know so these observations would have to remain “casual” anyway.

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Going off the numerous discussions about wild plants dug up or removed for close observation, it would only be wild for a short time or if preserved and stored such as in a herbarium. Follow-up observations of the living organisms after capture/transplanting become captive/cultivated. At least that seemed to be the consensus for plants, and also seems to apply to insects. E.g. if you collect caterpillars to raise butterflies in a cage, they are wild upon collection but captive while progressing through life cycle stages under your care.


I think there are several issues here:

First is that in this scenario you did intend to move marine life (live rock), you just weren’t sure what exact species were there. The goal was to seed the aquarium with a variety of lifeforms, and you are intentionally creating conditions that support those organisms. This is sort of akin to planting a seed intentionally, but not knowing what plant species the seed is of, or tossing a seed mix into a lawn or meadow without knowing the exact species. Those plants would still be cultivated, even if you didn’t know the exact species (or accidentally planted the wrong things!).

I agree that the initial organisms colonizing the rock could be considered wild - however, they’ve now (mostly at least) changed a life stage, which is a general cut-off for considering something to move into captivity (see discussion on bringing caterpillars/pupae into captivity to protect for transformation as @annkatrinrose mentioned). So making observations of a different life stage would be an issue.

If there was an organism that you definitely did not intend to come into the tank/didn’t expect to be on the live rock, I think that you could make a case for an unintentional introduction and that it might be wild (like a disease/parasite?), but that wasn’t in the original question.


If you observe them shortly after capturing, those are wild, but months after they could multiply and change life stages, which still counts as wild if you don’t care for them, but if you’re thinking if it’s worth observing, I’d went and caught more and observed them instead.

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I assumed that the author doesn’t plan to upload on iNat the lives of the creatures in the tank but their presence. Then, each organism would have one observation with place and date of collection from the wild (the latter is missing in this particular case).
If one collects caterpillars and raises them, isn’t it proper to add an observation with place and date of their collecting, but adding photos also of adult stage as often it is necessary to identify a species? There is also place for notes and the fact of collecting and raising caterpillars can be mentioned there.

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Yeah, good point. Seems best to leave them as captive. Thanks for your response!!

These critters have been in the tank for years now and have certainly gone through several life stages - one sea urchin, for example, I have watched grow from the size of a pinhead to adulthood, and even spawned in the tank. Some may well have even bred in the tank.

It is true that some critters were definitely unwanted introductions (eg. the mantis shrimp, notorious killers of snails, crustaceans, and on occasion, even fish), which could be argued was an accidental introduction, but it is a grey area and probably best to err on the side of captive.


But each subsequent photo, would be a separate obs at the new (correct) date.
Linked via comments, tags, a project, whatever works best for you.

I meant adding these photos in the observation concerning the initial observation, not creating a new observation for the subsequent life stage. Let’s say, I collect a caterpilar on 1.05. in a place X, take it home, and 3.08 I have a butterfly, and then I take its photos and put to iNat with date 1.05, place X and annotation that the butterfly emerged at home from the larva collected in the field. Is something wrong with recording it that way?
Anyway, I see the author decided to put “current” observations of the animals as captive and that’s also fine.

Yes, you should not do this - creating a new casual observation for the captive lifestage is best and then linking to it. Some potential issues with adding multiple lifestages of one individual to the same observation including annotating to lifestage and problems with phenology data. Also, iNat guidelines specify that an observation should be one interaction with a single individual at a specific place/time. For instance, an observation of the same individual a day later would be a separate observation. There’s a little leeway here (like bringing an organism back from a collecting trip and taking a pic a couple of days later), but several months and a different life stage seems too far removed.

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Backing up cthawley, and want to add that when you create a (casual) observation for the emerged butterfly, you can put that photo under the larval observation in the ‘notes’ section.

Just copy+paste the URL of the adult photo and integrate it via the html command (like I did here for a habitat shot).

The string should look like this, with the x’es as placeholder for the actual identifier:
<img src=>

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I would add, though, don’t be too disappointed if the observations you link in this way don’t all get to the same level. I have two linked observations, with notes in both explaining why I believe that they are of the same individual, yet that didn’t help the blurry one to get research grade like the clear, sharp one has. Apparently, being linked to a clearly identifiable observation of the same individual doesn’t count as sufficient evidence for identification.

I’ve encountered that, too, e.g. with plants at different phenology stages. I’ve even had identifiers insist on bumping seedlings back to genus level even though I had them linked to the flowering plants later that summer, arguing that there wasn’t enough proof they were the same plants.