All bark and no bite

The tiny black-clawed crabs that arrived in a holdfast six weeks ago are growing up. The largest, a male, was 5 mm. across the carapace; now he's three times that. He has chosen a hiding spot behind a big rock, but up against the glass - it feels solid, I guess, even if it's transparent - and I've been trying to get his photo. He usually responds by threatening me with dire harm.

"Armed and dangerous, I am!"

His multi-coloured shell and legs are good camouflage in the mess of shell pieces and stones he collects around himself. The back legs are usually raised, holding the rock behind him.

His usual pose; always with those dark pincers raised and ready for action.

When I give the tank a thorough cleaning, I remove the animals to a bowl first. I have to chase my speedy green shore crabs around and around for quite a while; even caught, they struggle to get free. These little black-clawed crabs, once I've removed their sheltering rocks, walk away casually; no worries. When I pick them up, they sit quietly in my hand, not even bothering to threaten me. But once in the bowl, they quickly scuttle under the closest shelter.

The second largest is a female, and very much in berry; her whole underside is a mass of dark eggs. She hides in a crack between two stones, and rarely shows more of herself than the warning pincers. Hers are mostly a dark brown colour.

And I haven't been able to lure her out into the open for a photo op. I haven't wanted to stress her by taking her photo on my hand, so I'll keep watching the door to her hideout, camera in hand.