The Salt Sac is a remarkable example of an intertidal succulent.
“Succulent?” you might wonder. “Aren’t succulents desert plants, like cactus, that live in the hot, dry desert?”
Well, yes. But actually a succulent can be any plant that has thick flesh to enable it to resist desiccation. And in that sense, the Salt Sac (Halosaccion glandiforme) is an outstanding succulent.
As both its common and its generic name imply (“halo” meaning “salt” and “saccion” “a sac” “bag” or “strainer”) this seaweed is basically a bag or sack, which is in turn filled with seawater.
But these features by themselves would not necessarily prevent the Salt Sac from drying out between tides. The seaweed’s flesh is also relatively thick, so that combined with water, enables this plant to retain its moisture when exposed to hot sun and drying wind.
The benefits that the Salt Sac has over other seaweeds can be illustrated by the example of several types of ‘sacks’ or ‘socks’ – one a nylon stocking, another a cotton athletic sock and the third, a neoprene bootie—all filled with water and then hung out to dry on a clothesline. Obviously, the bootie is likely going to be sopping wet long after the nylon stocking is bone dry and the cotton sock probably still damp.
The Salt Sac’s remarkable survival mechanisms also provides it an advantage when it comes to areas it can grow. While it tends to grow in a relatively narrow band of middle tidal rocks, and usually grows to be less than 10 inches in length, its range is huge. It can be found from Point Conception northward into Alaska… and then down into Russia. It was actually first described in Russia in the mid-1800s earning it the distinction of being one of the oldest known—albeit still rather poorly—of the northern Pacific seaweeds. (The Salt Sac is somewhat of a misfit seaweed as to color in that it is classified in the family Rhodophyta or red algae, but it is commonly a yellow-brown.)
To some persons who enjoy the more unusual cuisine, the Salt Sac is considered to be ‘succulent’ in the sense of ‘satisfyingly tasty.’ It is said to make a nice addition to soups, or even good consumed all by itself. How many other people would agree is hard to say, but at least one type of snail, the black turban (Tegula funebralis) is known to regularly dine on the Salt Sac.
Moreover, a copepod, Diarthrodes cystoecus, is completely ‘into’ the Salt Sac. This little shrimp-like crustacean inhabits the thick, water retaining, tissues. But like its host, not too much more is known of this remarkable creature.
Unlike looking for succulent cactus in the desert, remember—even though you are seeking a succulent here, dress for the cold wet, seashore, and not the hot, dry desert.