All California divers know and greatly admire giant bladder kelp (Macrocystis pyrifera). There is nothing like being 30 feet beneath the surface of the water and looking up in awe at the rays of light filtering down from above, glistening through the golden leaf-like blades of the giant kelp in a kelp forest.
Yet the kelp forest is home to other delightful species of kelp as well. Some of the prettiest are the remarkable bladder chain kelps, (Cystoseira spp.) The generic name for these plants is the direct equivalent of their English (“cysto” being the Greek for bladder or pouch and “seira” meaning chain or rope). And when mature plants, these chains of bladders are the most outstanding feature, not only in appearance but also in function.
For these tiny bladders are not just useful in keeping the plants afloat. They are actually the centers for reproduction—reproduction that in many ways has a lot in common with animals rather than plants.
With bladder chain kelp, the sexes are separate, on different individuals, meaning that there are female plants and male plants, but not both on one as does occur in other species. Both the male and the female plants develop those distinctive “rows-of-golden-beads” style bulbs as they get older. From within a bulb of the female plant, a single egg will emerge. From the male plant, there will appear 64 tiny sperms. Yes, sperms and egg, not all that unlike what animals produce. The coordinated release of sperms and eggs from all the plants in an area will occur according to certain tidal conditions. After the successful uniting of an egg and sperm, eventually a new plant will arise.
Not too long after the release of all their sperms and eggs, the mature “parent” plants will discard their delicate bladder chain growths for the winter. However, the entire plant does not die back, as does occur with other seaweeds. The lower part of the thallus or main section remains year after year, and after a while, tends to become rather woody and a dark blackish-brown color. This partial die-back may serve to prevent excessive damage during the stormy season. In other parts of the world, some individual bladder chain plants have been known to live as long as 50 years!
When California’s most common bladder chain kelp grows again in the spring and summer of the year, it can attain the height of 30 feet. The fern bladder kelp (C. osmundacea) has been given its specific name because its lower blades look so much like the royal fern (Osmunda sp.) of the eastern United States. Of course, its upper growth is still those pretty chains, giving the characteristic look of two unrelated plants just being stuck together. The fern bladder chain ranges from Washington to Baja California, from the lowtide zone to about 30 feet deep.
The other two California species have much more limited ranges. C. setchellii is found from San Luis Obispo County to San Diego, and C. neglecta is around just Catalina and San Clemente Islands. Yet regardless of the specific name of the latter, since it is around favorite dive destinations, it can’t be all that neglected!
For bladder chain kelps are the favorite places of many—and not just divers. It is one of the preferred abodes of tiny spirorbid worms, and many other creatures find refuge among the kelps’ labyrinth of branchlets. There are even certain types of epiphytic kelp associated with bladder chain kelps. Certain brown sac algae, Coiledesme spp., are found only on bladder chains, and nowhere else. Perhaps this is a bit extreme, but when divers have come to know and admire these remarkable and beautiful components of the kelp forest, they just might feel that it’s not all that bad a choice either.