Common name: Anemone Hermit Crab

General Information

The Anemone Hermit Crab (Dardanus pedunculatus) is a fascinating and unique addition to marine aquariums. Known for its symbiotic relationship with sea anemones, this hermit crab carries anemones on its shell for protection, creating a mobile fortress. Its striking appearance, with brownish-orange legs adorned with white spots, makes it a visually appealing inhabitant for aquarists seeking something out of the ordinary.

This species is widely distributed across the Indo-Pacific, from the Red Sea to Hawaii, and is commonly found in sandy or rubble areas near coral reefs. Its ability to adapt to various environments and its intriguing behavior make it a popular choice among hobbyists.

Care

The Anemone Hermit Crab is relatively hardy and can adapt to a range of tank conditions, making it suitable for aquarists with moderate experience. A tank with plenty of live rock and sandy substrate is ideal, as it provides hiding spots and opportunities for foraging. Ensure that the tank is stable and free of aggressive tank mates that might harass or harm the crab.

This species is known to "upgrade" its shell as it grows, so providing a selection of empty shells of various sizes is essential. Without suitable shells, the crab may become stressed or even attempt to steal shells from other hermit crabs or snails.

Diet and Feeding

Anemone Hermit Crabs are omnivorous scavengers, feeding on detritus, algae, and leftover food in the aquarium. They play a beneficial role in cleaning up uneaten food and debris, helping to maintain water quality. Supplement their diet with sinking pellets, algae wafers, and occasional meaty treats like chopped shrimp or fish.

Feed them sparingly, as overfeeding can lead to water quality issues. Observing their foraging behavior can help determine if they are receiving enough nutrition.

Behavior and Compatibility

The Anemone Hermit Crab is generally peaceful but can be territorial when it comes to its shell or anemones. It may occasionally clash with other hermit crabs or snails over shells, so providing ample resources can help reduce conflicts.

This species is reef-safe with caution. While it does not harm corals, it may inadvertently knock over or disturb delicate coral structures while moving around the tank. Its symbiotic anemones can also sting other tank inhabitants, so care should be taken when selecting tank mates.

Symbiosis

One of the most remarkable features of the Anemone Hermit Crab is its symbiotic relationship with sea anemones, such as those from the genus Calliactis. The crab carries these anemones on its shell, gaining protection from predators thanks to the anemones' stinging cells. In return, the anemones benefit from increased mobility and access to food particles stirred up by the crab's movements.

In captivity, this symbiosis can be maintained if the crab is provided with suitable anemones. However, the crab may also "steal" anemones from other tank inhabitants or even attempt to move corals onto its shell, so monitoring its behavior is important.

Health and Common Issues

Anemone Hermit Crabs are hardy but require stable water conditions to thrive. Regular water changes, proper filtration, and monitoring of water parameters are essential to their health. Avoid exposing them to copper-based medications, as these are toxic to invertebrates.

When selecting an Anemone Hermit Crab, look for active individuals with intact legs and claws. Missing appendages can regrow during molting, but a healthy specimen will have all its limbs intact. Ensure the crab has access to appropriately sized shells to reduce stress and promote natural behavior.

Habitat

In the wild, Dardanus pedunculatus inhabits sandy or rubble areas near coral reefs, often at depths of up to 30 meters (100 feet). Its natural environment includes plenty of hiding spots and access to shells of various sizes. Replicating these conditions in captivity will help the crab feel secure and exhibit natural behaviors.