Coconut crabs

Last week, we have received two new species  of hermit crabs: the electric blue hermit crab (Calcinus elegans) and the Halloween hermit crab (Ciliopagurus strigatus). We are still looking for two more to complete the Hermit crab from around the world exhibit. Next to their tanks at the Fundy Discovery Aquarium, you will also notice a panel telling the story of the coconut crab (Birgus latro).  At a maximum of 9lbs (4 kg), and over 16 inches (40 cm) long, I find this species very fascinating, as it is the largest land arthropod, and some say the largest land invertebrate in the world! However, this hermit crab is especially interesting because of its life cycle: it does not always behave like a hermit crab.

After mating on land, females carry their eggs under their abdomen until the eggs are ready to hatch. She then moves into the shallow ocean water, usually at high tide, to release the eggs that will then hatch in the water. The microscopic larvae float around for 3 to 4 weeks, after which they settle at the bottom and find an empty snail shell to live in, just like any other hermit crabs. They live underwater, sometimes coming out on land, and eventually choose to live permanently on  land, where they find empty broken coconut shells as an alternative to snail shells. They lose their ability to breath underwater, and their abdomen hardens. When they become adults, they no longer need an extra shell for protection, and they live like any other land crab. Coconut crabs can live 40 or 60 years. Coconut crabs live in the Indian Ocean and the central Pacific Ocean, where coconut palms grow. When living on land, they dig burrows in sand or loose soil.

A couple of months ago, our coordinator, Jim Cornall, went to visit a public aquarium in Tennessee and they a coconut crab on display (see photo). They come in beautiful colors like blue or bright orange. Quite amazing!