Hermit crabs usually use shells discarded by other creatures, such as whelks, to protect their soft and vulnerable abdomens.
Staff at the aquarium thought it would be interesting to see what the crabs did inside the shell and learn the answers to often-asked questions, such as how do the crabs manage to squeeze into such a small space? And just a week after two transparent glass shells were placed in a holding tank, one crab decided to claim one for its home.
Senior aquarist Matthew Crane said it would be difficult to replicate nature, but one crab had readily adopted the glass shell, with the second glass shell still to be claimed.
Centre manager Tessa Mills said it was now clearly visible how the crab twisted its abdomen around the central column of the shell, with the tip of the abdomen firmly holding the crustacean in place.
The glass shells were the first used at the aquarium, although similar ones had been used overseas, she said.
More glass shells had been requested.
University of Otago scientific glass-blower Anne Ryan was enlisted to design the shells.
She said it took her about a month to work out a method in which the shell looked good and sat correctly.
She was used to making unusual glass objects for the university, but it was the first time she had made shells.