Can the gastropod shells being worn by hermit crabs count as their own observations?

This is a question that’s always puzzled me. On one hand, they’re now part of the hermit crab, but on the other, they were once part of a gastropod and still provide valuable information about what gastropod species are present in the same area. And in some cases, the shell being worn might come from a species that’s not easy for humans to find.


I think they can be.

I have yet to make an iNat obs of a hermit crab though.


I think you answered it, they’re their own organism and of course count as separate observation, they’re not really part of crab who will change the shell after next moult.)


If you’re making an observation for the hermit crab, make sure the crab is actually visible. Otherwise it’s just a dead shell. But, yes, crabs can be a good way of finding interesting shells. Some gastropods are only known from crabbed shells.


Interesting! Can you give any examples of this? I am curious to know more


Yes, take pictures from different angles and duplicate your observation.
For hermit crab, shots of the legs and the head from sides, top and front, as well as a shot of the shell opening blocked by the pincer are great for identification.

(Some say you can whistle to get the crab to get out of its shell, it has never worked for me but it improves the mood.)


I have turned in hermit crab photos and included a clarification in the Notes that I was submitting the hermit crab. I’ve then used the same photo again, but noted that I was submitting the gastropod shell. It seems to work well, so long as the distinction is included in the notes as to what you seeking identification. I’ve done the same thing with a predator with its prey in its mouth, and with one bird chasing another in a photo.


Like @deboas I am also fascinated by this tidbit of information, and would like to know. I live far away from any ocean, but would love to know of shells ‘discovered’ through hermit crab observations.

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I am having trouble finding examples, but I am pretty sure I’ve read about such instances. They are probably from deep-water crab pots, where baited hermit crabs carry shells that are otherwise very difficult to come across. Not something the average tidepooler would encounter.


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