Something sharing my hermit crab shell identified!!

[Privateer]

So I have a white spot hermit that lives in my sump. I really like the big guy. I was watching him munch some scallops yesterday and saw something emerge from the back of his shell and take food and scoot right back. I managed to get a couple of poor pics today, and while I have no proof, I believe it to be a baby hermit crab. Opinions would be appreciated. 
 

[WV Reefer]

17 minutes ago, Privateer said:

So I have a white spot hermit that lives in my sump. I really like the big guy. I was watching him munch some scallops yesterday and saw something emerge from the back of his shell and take food and scoot right back. I managed to get a couple of poor pics today, and while I have no proof, I believe it to be a baby hermit crab. Opinions would be appreciated. 
 

How cute!
 

I have no idea if it’s a baby crab or shrimp though. 

[LazyFish]

Looks more like some kind of micro shrimp to me. Very neat.

[Tired]

Very interesting! Definitely not a baby hermit crab, but it's clearly a crustacean of some sort. I'd guess it's a tiny shrimp, and it may even be a species of shrimp that likes to live in inhabited hermit shells. Never heard of micro shrimp that live in hermit shells, but it sure sounds like a thing that could happen. Plenty of tiny animals live in plenty of inhabited places, or even inside other animals. 

 

It shouldn't harm the hermit (aside from stealing crumbs), and may even be helpful in keeping out any actual pests. If you can get any video clips of it, do show us!

[Privateer]

The only reason I suspected a baby hermit was the creatures claws match that if the hermit. It could very well be a small shrimp and I will definitely try to get video.

[LazyFish]

The claw shape somehow reminds me of a pistol shrimp especialy the larger one.

[Tired]

It does kinda look like a pistol shrimp, doesn't it? It's not nearly funky-looking enough to be a larval hermit, and anyway, at that size, it would probably be hermit-shaped and have picked a shell (or died from lack of one) by now. Whatever the case, the hermit's got a little buddy!

 

[Privateer]

I actually found some documentation that a type of shrimp does live in this species shells, but I could find  no pictures of these shrimp. Reef tanks never seem to stop surprising me , even after 20 years. 

[Toomanymatts]

I have nothing of substance to add, except that is rad.

[LazyFish]

Awesome I looked but couldn't find anything on it myself got a link?

[Privateer]

Link

 

https://www.researchgate.net/publication/260058512_Notes_on_the_behaviour_of_Heteromysis_harpax_a_commensal_mysid_living_in_hermit_crab_shells

[LazyFish]

Wow realy cool maby theres more than one in there! I guess you could get him a glass hermit shell and see if he takes it would be very cool to observe.

[Privateer]

 

 

50 minutes ago, LazyFish said:

Wow realy cool maby theres more than one in there! I guess you could get him a glass hermit shell and see if he takes it would be very cool to observe.

 

that would be cool but, the way he plows through the rock rubble in the sump, I’d be afraid he would shatter the shell 🤣

My plans are eventually to get him his own tank, maybe let some green star polyps go wild in there because I think that’s the only think he wouldn’t devour. 

 

[Tired]

https://www.google.com/search?q=Heteromysis+harpax&sxsrf=ALiCzsbxYskIkMgGD-qqqKyJI5sBZc-Jlw:1653234092338&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjXoLf2uPP3AhXemWoFHengBjAQ_AUoAXoECAEQAw&biw=1920&bih=969&dpr=1

Looks like it's not that. Those are a mysis shrimp sort of animal, and this little critter has large claws and appears to be perched instead of swimming.

[LazyFish]

Intresting none of the mysis have claws that I see but there are sevral mysis that do associate with hermits.

[Privateer]

 

got some vid of him …he’s definitely red and yellow but it’s hard to tell in this vid

 

 

 

https://public.fotki.com/Privateer/reef/1653341271130.html

[Tired]

Aw, look at the wittle guy go!

 

You know what that body shape reminds me of? Emperor shrimp. https://en.wikipedia.org/wiki/Periclimenes_imperator They live on sea cucumbers and nudibranchs. I wonder if this is some distant relative that lives with hermit crabs. Clearly this particular one wants to live there, as I'm sure otherwise it would have long since found a less mobile hidey-hole. 

 

It's a bit like a pistol shrimp, but doesn't seem to have the giant snapping claw. Do keep us updated on whether it grows or does anything else unusual. If this is in fact a shrimp that lives with hermit crabs, you might actually have found a new species. 

 

Where'd you get this hermit? Can you email them and ask if they've seen this before? 

[WV Reefer]

10 minutes ago, Privateer said:

 

got some vid of him …he’s definitely red and yellow but it’s hard to tell in this vid

 

 

 

https://public.fotki.com/Privateer/reef/1653341271130.html

It’s so cute! 

[Privateer]

even better video!!!

 

https://public.fotki.com/Privateer/reef/1653342547644.html

 

I got him at lfs…they don’t know anything lol

[Tired]

 

Oh, well, that's a pistol shrimp. That is 100% a tiny pistol shrimp, living in a hermit crab's shell. Or mayyybe a very pistol-shaped shrimp that has a large pinching claw for some reason, but, no, that's a pistol shrimp. The face and everything is right. 

 

The wobbling motion it does sometimes is interesting. I wonder if that's meant to make it look less like a shrimp crawling around, or if it's a behavior meant to somehow communicate with a symbiotic buddy? 

[LazyFish]

That's ok yes looks like tiny micro pistol shrimp but the way that thing moves is just wrong!

I cant recall any type of pistol with those markings either.

But the movements just ew!

[Privateer]

19 minutes ago, LazyFish said:

That's ok yes looks like tiny micro pistol shrimp but the way that thing moves is just wrong!

I cant recall any type of pistol with those markings either.

But the movements just ew!

I’m wondering if movements are due to water flow…when I took the vid the crab was under some decent flow from water leaving one chamber of the sump 

[Tired]

The way it moves reminds me of two things. One is stick insects and chameleons, the way they sway to look like moving debris instead of moving animals, and the other is how some anemone shrimp move. I think we might be looking at a camouflage behavior. Some animals move oddly, trying not to appear like they're an animal walking around. 

 

Have you sent this footage anywhere? I'd be really curious to show it to some experts and ask if anyone has seen anything like this, particularly now that you have some clear video. 

 

 

 

[Privateer]

38 minutes ago, Tired said:

The way it moves reminds me of two things. One is stick insects and chameleons, the way they sway to look like moving debris instead of moving animals, and the other is how some anemone shrimp move. I think we might be looking at a camouflage behavior. Some animals move oddly, trying not to appear like they're an animal walking around. 

 

Have you sent this footage anywhere? I'd be really curious to show it to some experts and ask if anyone has seen anything like this, particularly now that you have some clear video. 

 

 

 

I have no idea who to send it to. If you have any ideas, please share because I’d love to learn about this little guy.

[Tired]

I wasn't entirely sure either, but I poked around a little, and I found a marine biologist who's inviting people to ask them questions. http://www.heatherspence.net/eng/contact/ask-a-marine-biologist/

 

You might also try emailing any sort of local aquarium or marine research institute, telling them you have what appears to be a pistol shrimp living inside the shell of a hermit crab, and asking if you can send them pictures for someone to have a look at. Scientists of the natural world generally love being sent cool mystery creatures.