Hermit Crab Shells
How To Measure Hermit Crab Shells
Hermit crabs need to trade in their shells for bigger ones as they grow. To provide an appropriate selection, you will need to measure the shells to ensure they are big enough.
A shell is measured across the widest point of its opening. Using a ruler, carefully measure your hermit crab’s existing shell. The diameter of the shell at its widest point is what you need to note down. Once you have your measurements, you can do the same for potential new shells.
New shells should be roughly a ¼ inch wider than the hermit crab’s existing shell. Pick 3-5 new shells that vary in size to give the hermie a few options. It is also wise to match the general shape of the existing shell, especially at the opening. “O” shape and “D” shape openings are the most popular with hermit crabs.
Hermit crabs are known to conduct “home improvements” on shells to make them more suitable for each hermit. It is normal for these critters to modify their homes, even if it’s a perfect size.
Hermit Crab Shell Size Chart
Here’s a quick chart to reference when sizing up your hermit crab shells. Compare the opening of your hermit crab’s existing shell to determine which size category it fits into:
| Small Hermit Crab | 3/8 – ½ inch opening |
| Medium Hermit Crab | ½ – 1 inch opening |
| Large Hermit Crab | 1 – 1 3/8 inch opening |
| Jumbo Hermit Crab | 3 inch or larger opening |
Remember, the new shells need to be up to ¼ inch wider than the existing shell. This gives your hermies room to grow and maneuver. After a molt, they’ll rely on having extra space and will turn down shells that don’t fit the bill.
