Hermit crabs eating urchin spines?

Atrumblood

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I recently acquired a small tuxedo urchin last week. It was doing fine as far as I could tell. It was not dropping spines and did a good amount of eating.

I caught my Halloween hermit crab hanging off of my new urchin picking at it. It appeared as thought it was trying to pull out the urchin's spines. So I separated them.

Today I get home from work and my urchin is missing 3/4 of its spines.

I don't think they fell out as I would expect to see spines all over the bottom of the tank.

Would any of you agree that my crab ate the spines?

Water Parameters:
Nitrates: 8.3
Calcium: 405 ppm
Alkalinity: 159 ppm
Salinity: 1.025
Temperature: 25.3C
 
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anthonygf

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I recently acquired a small tuxedo urchin last week. It was doing fine as far as I could tell. It was not dropping spines and did a good amount of eating.

I caught my Halloween hermit crab hanging off of my new urchin picking at it. It appeared as thought it was trying to pull out the urchin's spines. So I separated them.

Today I get home from work and my urchin is missing 3/4 of its spines.

I don't think they fell out as I would expect to see spines all over the bottom of the tank.

Would any of you agree that my crab ate the spines?

Water Parameters:
Nitrates: 8.3
Calcium: 405 ppm
Alkalinity: 159 ppm
Salinity: 1.025
Temperature: 25.3C
Yup, don't trust them. Got rid of all my hermits for destroying my branching monti, many of them would climb up the branches breaking them off. Before and after. I would pull off a couple one day, the next day there would be the ones I pulled off and some of their cousins. Got fed up and rehomed them.
 

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Atrumblood

Atrumblood

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Also how new is the tank? Maybe they didn't have enough food. I only have snails in my 75 now. That monti was 4-5 years old.
My tank is nearly 5 months old. Pretty sure they have plenty to eat as I am deep into the ugly phase right now.

I removed both of my hw crabs and put them in my sump where they await deportation back to the fish store.

My urchin is still alive and doing his best with the few spines he has left. Seems like he will pull through.
 

anthonygf

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Found this info on Salty Bottom Reef Co. I have purchased from them in the past with good results.

The Halloween Hermit Crab consumes a large variety of foods including scavenging for uneaten food, but also various types of algae and cyanobacteria. These crabs will also happily accept meaty food such as clams, fish, or mussels. Halloween Hermit Crabs have been known to attack other Hermit Crabs or Snails for their shells, it is always a good idea if housing any Hermit Crabs to have extra shells so that they are readily available. The Halloween Hermit Crab can also get to be around 2 inches, which is relatively large for a hermit crab. This can cause it to disrupt rock work or corals that are not secured.
 
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anthonygf

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My tank is nearly 5 months old. Pretty sure they have plenty to eat as I am deep into the ugly phase right now.

I removed both of my hw crabs and put them in my sump where they await deportation back to the fish store.

My urchin is still alive and doing his best with the few spines he has left. Seems like he will pull through.
Hope he does. The Halloween Hermit may eat clams? No way, I have a large clam.
 

Suohhen

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Algae, especially established algae is not necessarily something all hermits will go after, scarlets are the best bet but even so I always make sure my CuC is getting some meaty food to eat. Either way now that it has a taste for urchin you are best off getting rid of it as it is not likely to change its behavior.
 

anthonygf

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Algae, especially established algae is not necessarily something all hermits will go after, scarlets are the best bet but even so I always make sure my CuC is getting some meaty food to eat. Either way now that it has a taste for urchin you are best off getting rid of it as it is not likely to change its behavior.
Was just going to say that. Yes if they have a choice of spinach or steak, steak wins.
 

BloopFish

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Tons of crabs in the wild will eat an urchin, especially a sickly one. The roe of an urchin is delicious, almost every fish and crab would devour as much as they could. I think what happened to you is a mixture of a hungry hermit crab that has a particular taste for animals and an urchin who is slightly weak due being very new. Also Tuxedo urchins have such small spines, I'd personally go after them first to eat.
 
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