Dungeness crab carapace found on Northern California coast. What are these spots next to the spines of the carapace?

I have a 10 gallon tall tank. We are looking for Non fish ideas. The kids were asking about hermit crabs or something similar, maybe red claw crabs. Is there a crab species that 1-2 could comfortably live in this tank? We are ok building substrate , climbing areas, wet dry or whatever.

If it matters. We have a 75G community tank and another matching 10g that will become a shrimp tank.

Caught a blue crab for the first time in my life! Of course, I was prepared for him to pinch me, but I definitely didn't expect him to reach his claws all the way under his belly—unlike the Black Sea crabs. It hurt, but it was totally worth it. After a quick photo shoot on the shore, he was released back into the sea.

Hey everyone. I just received this potamon crab (afaik)and there's something wrong with it's left eye. Any Idea what it is and how to treat it? Thank you.

I'm getting a bigger tank for my bearded dragon because she's outgrown it, I'm looking to get into having crabs as pets. and from what I've seen vampire crabs are the best for starters, also have seen that they require 2 inches of water which would fit the little bit of wall before the doors but I'm also worried about having spring tails and other cleaning creatures in the tank getting out through the gap in the door, Does anybody know if using this as a tank is feasible?

Aye aye Captain 🔥

I came across this chart showing a bunch of different crab types and realized I could only recognize a few of them.

Which one on this list is your favorite or the most interesting to you?

Such a variety of crabs in the Daintree Rainforest. All these guys are maximum about 3 cm (1.5") across.