The Hitchhiking Anemone
Tagging along with friends on a journey is a great way to unwind, and the hermit crab anemone takes this idea to another level. Most anemones spend their entire lives glued to one spot, looking like colorful sea flowers that offer shelter to animals like clownfish. Anemones from the genus Calliactis, however, choose a far more adventurous path by hitching rides on the back of hermit crabs.
This partnership is an example of symbiotic mutualism, where both animals benefit from their association. The anemone serves as an active defence system for the crab, using its stinging tentacles to drive away predators like octopuses and other shell crushing crabs. In exchange, the mobile crab carries the anemone into surrounding water currents, making it much easier for the anemone to feed on drifting food and plankton.
A hermit crab searching for its companion will tap and gently stroke the base of an anemone on a rocky shore, sending a signal that it is time to climb aboard. In other cases, an eager anemone will wiggle onto a resting hermit crab and anchor itself to the shell by itself!