How do crabs grow?

1. 1

   Wobble says

   A crab wears its hard shell on the outside, and that shell can't grow. So to grow, the crab takes in lots of water, and crack! The old shell splits open. The crab backs right out, wearing a new soft shell that's a little bigger than before. That's called moulting.

   For ages 4–7
   Hear Wobble

   Checked against Dungeness crabs of Glacier Bay (U.S. National Park Service)

2. 2

   Why does a crab hide after moulting?

   A brand-new shell is as thin as paper, so it can't protect the crab yet. The crab buries itself in the sand for a few days to stay safe. Bit by bit, the new shell hardens. For a grown-up crab, it takes about six weeks to get properly hard again.

   For ages 6–9
   Hear Wobble

   Checked against Dungeness crabs of Glacier Bay (U.S. National Park Service)

In Lil' Phil, reaching the bottom of this wonder earns a sticker for Wobble's collection.

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