are often abundant in the mid- and low intertidal regions, distributed from Alaska to central California.
Acrosiphonia coalita.
Acrosiphonia coalita and detail (right) showing characteristic hooks.
56 | Filaments
Pacific Seaweeds
Cladophora Green tuft
Class Siphonocladophyceae Order Cladophorales Family Cladophoraceae
Number of Species
Cladophora (Greek=branch bearer) is a complex tangle of species that requires investigation; currently there are eight species listed in our area. It is an example of a complex assemblage of filamentous seaweeds including Rhizoclonium.
Description
Plants are typically densely branched but lack the hooks of Acrosiphonia (p. 55) and therefore form loose clumps or extensive mats, which may reach 30 cm (12 in) in length but are usually less than 5 cm (2 in) long. The cells are microscopic and multinucleate. Plants are usually attached to rock.
A freshwater species, Aegagropila linnaei (formerly known as Cladophora aegagropila) forms filamentous balls that may reach 30 cm (12 in) in diameter. The balls gracefully and repeatedly move from lake bottom to lake surface. At sunrise the balls are lifted off the lake bottom by oxygen bubbles produced by photosynthesis and trapped by the filamentous ball. When the ball reaches the surface, some of the oxygen is released to the atmosphere and the ball
Tufts of Cladophora sp. at low tide.
Cladophora columbiana and detail of filament arrangement (right).
Green Seaweeds | 57
Identifying Pacific Seaweeds
descends until enough oxygen is produced to lift it again. In Japan, where the species is known as Marimo, people were so captivated by this activity that they imprisoned virtually all the wild Aegagropila balls in their private pools. Emperor Hirohito recognized the danger to the species and, upon releasing his Aega-gropila balls, decreed that the species be protected. A Japanese postage stamp commemorates this event, and A. linnaei has the distinction of being the only species protected by Imperial decree.
Habitat & Distribution
Cladophora is found in high tide pools as well as on lower exposed surfaces of the mid- and low intertidal regions from Alaska to Mexico.
Derbesia Green sea grape
Above: Derbesia marina (filamentous phase). Photo by Gary Saunders
Right: Derbesia marina (arrow shows spherical phase) atop a crustose coralline-encrusted limpet. Photo by Russ Norberg
58 | Filaments
Pacific Seaweeds
Class Ulvophyceae Order Bryopsidales Family Derbesiaceae
Number of Species
Derbesia (after Alphonse Derbes, a French phycologist) is locally represented by D. marina, one of the approximately 20 species found worldwide.
Description
Derbesia marina has a life cycle that consists of two different morphologies: an inconspicuous branched filamentous phase lacking normal cross-walls, alternating with a unicellular spherical (up to 1 cm/0.4 in in diameter) phase. The filamentous plants form fuzzy tufts with branches up to 1.5 cm (0.6 in) long.
The spherical phase produces sexually fusing gametes fortnightly. These gametes fuse, initiating the spore-producing filamentous stage. Spheres with dark patches produce female-like swimming gametes, and spheres with pale, yellowish patches produce male-like swimming gametes. These patches explode, deflating the spherical cell and releasing the gametes. The gametes fuse in the surf zone (no small feat!), settle out and develop into the filamentous phase. Over the following two weeks, the sphere is repaired and re-inflated, and more gametes are produced. These observations were first made by G.M. Smith (Stanford University) in 1930. Professor Smith produced the first popular flora for our coasts: Marine Algae of the Monterey Peninsula (1940). This flora, with its exquiste drawings, has morphed into the compre-hensive Marine Algae of California (1976).
Habitat & Distribution
Both phases of D. marina may be found on rock or crustose coralline sea-weeds in the low intertidal and subtidal zones of wave-swept shores. The filamentous phase may also be found on sand. It is commonly distributed from Alaska to southern California.
Bryopsis Green sea fern
Class Ulvophyceae Order Bryopsidales Family Bryopsidaceae
Number of Species
Bryopsis (Greek=moss-like) is represented by three species in our area, B. corticulans, B. plumosa and B. hypnoides, of the more than 50 species known worldwide.
Green Seaweeds | 59
Identifying Pacific Seaweeds
