Crabs crawing out of tank

i`ve never seen hermits do it but i`ve had the odd snail crawl out of the water but not out of the tank very tend to go back in tho but this dose not happen very often for me
 
i had a 2inch blue crab (the kind you eat) crawl out of the 72G tank and my dog let me know it so i put him back in and secured the glass lid better. hes still doing well
 
I have a pile of snail shells behind my tank.
 
How are the crabs even managing to get to the top of the glass? The siliconed corners? Rock piled to the top? Batman crabs?

Its the stupid silicon corners. My hermit got pretty far up.

Based on my experience the hermit crab will usually go up part way and then get tired and go back down. They aren't very adventurous.
 
In the freshwater tanks they can climb air tubing right out of the tank, Of course, I won't have any air line tubing in the saltwater tank.

My fiddler crabs would either climb my heater cord to the top of the tank and then get stuck on the plastic lid or they would climb to the top of the plants in the tank and jump across to the filter intake tube and climb up and out of the tank and sit ontop of my penguin 350.
 
I had 1 fiddler crab that died a year ago. I had it in an eclipse system so the top was completely covered, but almost everyday I'd find him sitting up on top of the filter. He was cool, the only crab I've ever owned. I look forward to having at least 1 oe 2 crabs in my saltwater tank.
 
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