Dardanus pedunculatus is another type of hermit crab also called the anemone hermit crab. They have distinctive green eyes and beautiful anemones on their shell.
Like the ordinary hermit crabs, anemone hermit crabs live in shells which protect soft part of their bodies (see our blog for more information and photos). These crabs in addition adorn their homes with anemones. Apart from making it beautiful and ornate, it is a highly fruitful and mutually beneficial (symbiotic) relationship. When you snorkel or walk on a reef and your eye catches a movement of something weirdly shaped, you can be assured that you are seeing an anemone hermit crab – beautifully decorated as if in a hurry to a fancy dress party.
There are usually two types of anemone which can be found on the shell: one with Wilma Flintstone type of “hair” and another is a small white anemone living closer to the crab’s head. Sometimes anemones are closed and you can see just the lumps.
Sometimes you see anemones fully flared and they create some intricate shapes.
And sometimes some on duty while others are asleep.
This relationship works well both ways. Hermit crabs put anemones on their shells and carry them around. This provides anemones with free transportation and helps them get more food as they pick up scraps from meals eaten by the crab. Riding on a crab also helps anemones to disperse. Anemones in turn ensure good camouflage and protect their crab as anemones are venomous for most of the predators. You can often see that when the anemone hermit crab runs and you put your hand in its way, it would turn around with the biggest anemone facing you and will retract into its shell.
Anemone hermit crabs molt in exactly the same way as hermit crabs. When they need to change their shell, they will carefully move their anemones across onto the new one and often will add some more. Sometimes there is no need for a crab to change his shell as anemones will have created enough shelter and protection by secreting shell like substance, which extends and enlarges the shell of its crab.
There is quite a number of such symbiotic relationship in nature and underwater in particular. Some very unlikely creatures live together in peace and harmony, helping and protecting each other. And at times I wonder why people cannot have the same peaceful existence with nature and with one another…