28 July 2010

Giant spider crab comes out of her shell

Ingrid Sinclair
The giant spider crab emerges from her old shell, all pink and brand new. Photographs by Jacinta Subjee

One of the Aquarium’s giant spider crabs, who can be seen in the Oceans of Contrast: Atlantic Ocean Gallery, has moulted. She started moulting early yesterday morning, and by 15h00 had completely freed herself from her old shell.

Spider crabs are the largest crustaceans in the world – males grow to approximately one metre in length with a four-metre leg span. These crabs live at depths of approximately 400 metres and in temperatures between 11ºC and 14ºC.

Very little is known about the biology of giant spider crabs. It is virtually impossible to determine their age and we do not know when they reach sexual maturity, or how they breed.

As with all crustaceans, continual growth is impossible for giant spider crabs because of their hard exoskeletons. To grow, the crabs have to shed this exoskeleton by moulting, a complicated process which can take up to two days. Each moult is potentially life-threatening as the crab can become entrapped in its old shell. Even if the moult is successful, the sheer effort is sometimes so exhausting that the crab dies soon afterward.

“What an absolutely amazing experience!” said the Aquarium’s Tourism Coordinator Renée Leeuwner, who was on the scene and tweeted the events as they happened. “The spider crab has completely come out of her old shell and she is looking beautiful. She now has to wait until her new shell hardens before she can resume her normal activities. With her shell being so soft, she is very vulnerable, so we will keep her separated from the rest for another while.”

Aquarist Tertia Greenstone is keeping a close eye on the crab’s progress.

The Aquarium put up a sign to tell visitors that the crab was moulting
The process began very slowly
Each moult is potentially life-threatening as the crab can become entrapped in its old shell
The process sped up as she pulled her legs out of the old shell and started moving backwards out of it
blog comments powered by Disqus