Can Air Ferns Be Planted in Dirt?

What an "Air Fern" Is

• The "air fern" is the skeleton of a colony of marine creatures, Sertularia argenta, a relative of coral. While the remains of S. argenta do look much like a fern, the intricate branches are actually made of chitin, built into a fern-like shape by the individual creatures which lived within it. Though it was once rooted to the sea floor, once the colony die the skeleton washes inland into coastal areas.

How They Live

• When living, a colony of Sertularia argenta is somewhat like that of a colony of insects. They live in a communal structure which they build out of chitin, and each individual polyp has its own function within that colony. Some gather food from the ocean around them, while others concentrate on reproduction or building their structure. The structure isn't just a habitat, however. Through it, the polyps can share nutrients, allowing the food gathering polyps to feed the whole community.

How They're Gathered

• Often found in the North Sea, "air ferns" are collected by boats which dredge streams, rivers and estuaries where the skeletons wash up after the colony within has died. Once they're gathered they are dyed. Although most are dyed green and then sold as "air ferns," some are dyed in more exotic colors and weighted in order to be used as decoration in aquariums.

How They're Sold

• The advertising of the "air fern" is often misleading. Not only have some companies claimed that S. argenta skeletons are living plants, but that they have a fragrance which drives away insects. Such claims have been successfully challenged in the UK, when in March 2008 the Advertising Standards Authority ruled that calling the remains of S. argenta a plant was misleading, and that the claim of an insect repellent fragrance was unsubstantiated.

Decoration

• While they may not be living plants, S. argenta are very fern-like in appearance as well as texture, and can be used as decoration. If properly colored with water-proof dyes, they hold up well in aquariums. They can create the look of a fern outside the aquarium, without any care or feeding necessary. However, if they've been stored for a while, they can develop an unpleasant odor and may need to be aired out before you use them in your decor.