I had to do some quick research on the life expectancy/life span of a marine tank blue knuckled hermit crab. The reason being, my particular blue knuckled hermit crab has seemed to have kicked the bucket. He’s been in my marine tank since the first day I actually added living creatures to it.

I had set up the tank originally at my office. At the time, it was the office tank. A 75 gallon saltwater tank. We stocked it with 5 Cardinals, a Yellow Tang, a Clownfish, a Longnose Butterfly Fish and a Blue Knuckled Electric Hermit Crab.

After having gained sole possession of the tank through business buyouts, I moved it home. Then a couple months later I had to move it to a different apartment. I had moved the tank twice within a 4 month period. The tank has a total lifespan of about 2.5 years today. The only original fish left at this point are the Hermit Crab and one of the Cardinals.

And now I think the crab is out for the count. He usually disappears into his shell for 2-4 days after molting, but this time it’s been about 5 days and there’s no signs of him moving. He might be in hermit crab purgatory.

Back to the quick research, I found the common life-expectancy for hermit crabs to be around 5 years on average:

Hi can you tell me the average life span of a hermit crab please. Steve in England
<Hi, Steve. It depends on the type of hermit crab, land, inter-tidal, marine, etc. Should be around 5yrs on average, maybe up to 10 for the larger species. -Gage>

My crab made it about 2.5 years. That’s not too bad, I can live with that.

If he is indeed a goner, I’ll need to find a replacement to scavenge the tank. It’ll be interesting to see what I come up with.