A Few Facts About The Anemone Crab
The Porcelain Anemone Crab - There are several species of anemone crab to be found, with the Porcelain Anemone Crab being the best known and most numerous. The Porcelain Anemone Crab is widely distributed throughout the South Pacific, most often found on coral reefs and, not surprising, where various species of anemones are to be found. This crab has a symbiotic relationship with many species of anemone; including the Carpet Anemone which is generally regarded as unsafe to be around if you are a saltwater denizen. This species of anemone crab and the Clown fish are two saltwater animals that enjoy more or less of a peaceful coexistence with the carpet anemones and other anemones as well.
The anemone crab and the Clown fish, and other anemone fishes as well, don't always get along however and turf battles often result. The anemone crabs, often much smaller than the anemone fishes, usually withdraw to a safe place, and spend much of the time living near the stalk of those types of anemones which have a stalk. The Porcelain Anemone Crab, though by no means rare, is not often observed in the wild as it will usually try to keep out of sight of an approaching swimmer or diver. When they are captured, and raised in a home saltwater aquarium, they are generally easy keepers. The anemone crab does not have to have an anemone in the neighborhood to survive, but its chances of survival are better when anemones are present. This is especially true in an aquarium. The anemone crab eats mainly plankton and tiny bits of food, much as is the case with many types of anemone. A pair of anemone crabs will often share a single anemone and together attempt to defend their territory against other crabs or fishes.
These crabs differ from the crabs we most often see as they have three, rather than four, pairs of walking legs. The crab's mouth parts include a pair of large basket-like appendages which wave through the water, capturing zoo plankton and other small tidbits of food.
Traveling Anemones - While the Porcelain Anemone Crab and other species of anemone crabs may stay in the vicinity of a single anemone, the hermit crab takes a far different approach. While hermit crabs are usually not thought of as being anemone crabs, some have earned this distinction. The anemones involved in this symbiotic relationship however tend to be rather small in size, as they travel about attached to the hermit crab's shell. This arrangement seems to benefit the anemone considerably. How it benefits the crab isn't always clear, but when the hermit crab discards its shell in favor of a larger one, it often transfers the anemones to its new shell! Obviously then, having an anemone or two on your back must have some advantage.
While the Porcelain Anemone Crab is an almost ideal candidate for the saltwater aquarium, the same cannot be said for most species of hermit crabs. While some species, as mentioned, will coexist nicely with anemones to the extent of even carrying them around, many species will simple eat any anemone they happen upon. Many hermit crabs will prey on small fish as well. In keeping a saltwater aquarium, it's necessary to pay close attention to whom the prospective inhabitants are going to be, as many simply don't get along, and if you're not careful you might just end up with a tank containing only a single surviving species. Some species of anemone, like the carpet anemone, and especially the Atlantic Carpet Anemone will eat anything and everything. The same can be said for certain fishes, and the same can be said for certain crabs. If you want an anemone, some fish, and a crab or two in the same tank, the choices as to what will work out are somewhat limited.
Still, life is full of challenges, and having a saltwater aquarium can certainly be one of them.