its called a pincer
The males wave it over their heads to get the female's attenteion.While doing that it looks like their fiddling.Thats why there called fiddler crabs.
Chela
yes
by rubbing their big claw on there body
No.
they start to chase each other and then claw each other
red clawed crabs eat best when no one is around or watching them (at night).
It will drasticly reduce their life they are semi aquatic needing both dry lanf and water
Crabs raise one of their larger claws, often referred to as a "major claw," as a display of dominance and to signal their readiness to defend themselves or establish territory. This behavior can also be a part of mating rituals, where the raised claw attracts potential mates. Additionally, the raised claw helps in communication with other crabs, conveying aggression or submission depending on the context.
Hermit crabs usually , if not always, have one large claw and one smaller claw.
They dip their big claw in the water and drink the drops on the claw, they do that over and over again until they are full.
In most cases yes, unless they lost their claw due to stress or sickness