How do crabs grow bigger?

Crabs grow bigger through a process called moulting or ecdysis. Here's a step-by-step explanation:

1. Exoskeleton: Crabs have an external skeleton, known as an exoskeleton, that provides protection and support to their bodies.

2. Growth: As the crab grows, its body becomes too big for its current exoskeleton. This triggers the moulting process.

3. Withdrawal of Body: Before moulting, the crab withdraws its body from its old exoskeleton. It detaches the exoskeleton from the inside by releasing specific enzymes.

4. Formation of New Exoskeleton: Underneath the old exoskeleton, a new, larger exoskeleton begins to form. This new exoskeleton is initially soft and flexible.

5. Shedding: The crab then sheds its old exoskeleton. The shedding process can take several hours, and the crab is vulnerable during this time.

6. Expansion: After shedding the old exoskeleton, the crab's body expands. This expansion is facilitated by the soft and flexible new exoskeleton.

7. Hardening: Once the crab has expanded its body, the new exoskeleton begins to harden. It absorbs calcium and other minerals from the water, making it rigid and strong.

8. Growth Complete: The moulting process is complete when the new exoskeleton is fully hardened. The crab can now continue to grow until it reaches the next moulting stage.

The frequency of moulting varies among different crab species and depends on factors like age, environmental conditions, and availability of food. Younger crabs tend to moult more frequently than older ones.

After moulting, crabs are typically at their most vulnerable and soft-shelled. This makes them more susceptible to predation and cannibalism by other crabs. To protect themselves, crabs often seek shelter or hide until their new exoskeletons harden.