Molting
The Florida stone crab loses its limbs easily to escape from predators or tight spaces, but their limbs will grow back. When a claw is broken such that the diaphragm at the body/claw joint is left intact, the wound will quickly heal itself and very little blood is lost. If, however, the claw is broken in the wrong place, more blood is lost and the crab's chances of survival are much lower. Each time the crab molts, the new claw grows larger.
The crab only molts at night or in night-like conditions due to the crab being extremely vulnerable to predators without the protection of its shell. If the crab is becoming too large for its shell and the sun is up, the crab releases a hormone from a gland located on one of their eye stalks called the x-organ. This hormone prevents the crab from molting from its shell until it finds a safe place to molt or it has become dark enough outside to molt in safety.
Read more about this topic: Florida Stone Crab