Common name: Hermit crab anemone

General information

The Parasitic Anemone, Calliactis polypus, is a species of sea anemone that is well-known for its unique symbiotic relationship with hermit crabs. It is not parasitic as its common name might suggest; rather, it forms a mutualistic association with various species of hermit crabs. This anemone is characterized by its long, slender tentacles and a range of colors from tan to greenish or brownish hues.

Care

Calliactis polypus is an interesting addition to the reef aquarium due to its symbiotic behavior. It requires a tank with stable water conditions and moderate to strong lighting. Adequate water flow is also necessary to mimic its natural environment and to keep the anemone healthy. It can be fed a variety of meaty foods, including small fish, shrimp, and other prepared foods for carnivores.

Reproduction

In the wild, Calliactis polypus reproduces both sexually and asexually. In the aquarium, they may reproduce through pedal laceration, where new anemones form from pieces of the base that detach from the parent anemone. This can lead to a proliferation of anemones in the aquarium if conditions are favorable.

Symbiosis

The most notable aspect of Calliactis polypus is its symbiotic relationship with hermit crabs, particularly those in the genus Dardanus. The anemone attaches to the hermit crab's shell and provides it with additional protection through its stinging cells. In return, the hermit crab offers the anemone mobility and access to food particles, enhancing its chances of survival.

Habitat

Calliactis polypus is typically found in the Indo-Pacific region, attached to substrates in shallow waters. They are often associated with coral rubble and can be found at various depths, usually not exceeding the reef crest zone.