Right: Rhizoclonium lubricum filaments, reminiscent of green fishing line.
Green Seaweeds | 53
Identifying Pacific Seaweeds
Class Siphonocladophyceae Order Cladophorales Family Cladophoraceae
Number of Species
Rhizoclonium (Greek=root) contains 30 species and forms. Locally, this genus is represented by one species, R. lubricum; however, the distinction between Rhizoclonium and other unbranched green filaments, like Chae-tomorpha, is ripe for study. This species was formerly known by the more suggestive name Lola lubrica.
Description
Rhizoclonium lubricum is an unbranched and usually unattached filament. Its multinucleate cells are invisible to the naked eye and its overall look and feel are reminiscent of green fishing line. Plants are usually in excess of 20 cm (8 in) long.
Habitat & Distribution
Rhizoclonium lubricum is often found in wave-sheltered waters, entangled with other attached seaweeds in the mid- to lower intertidal region, from BC to central California.
Urospora Hanic’s green barrels
Urospora sp. Photo by Gary Saunders
54 | Filaments
Pacific Seaweeds
Class Ulvophyceae Order Ulotrichales Family Ulotrichaceae
Number of Species
Urospora (Greek=tailed spore, named after a microscopic stage in the life cycle) is represented locally by four species: U. wormskioldii, U. penicilli-formis, U. neglecta and U. doliifera.
Description
Urospora is an attached, unbranched filament composed of large bar-rel-shaped cells, visible to the naked eye (but a magnifying glass helps). The filaments may reach 30 cm (12 in) in length but are usually less than 10 cm (4 in) long.
Locally, Louis Hanic (professor emeritus, University of Prince Edward Island) was able to link ‘Codiolum’, a microscopic bowling pin–shaped unicellular green alga that lives inside fleshy red algae, to the life cycle of Urospora (see Unicellular Forms, p. 70). Previously, ‘Codiolum’ was classified in a distant and distinct group of green algae. This discovery was the culmination of four years of graduate research (University of British Columbia, 1965) by a former antique furniture restorer from Secovce, Czechoslovakia.
Habitat & Distribution
Urospora grows on rock and wood in the mid- to high intertidal region from Alaska to southern California. Its discovery would enrich collectors’ life lists.
Urospora penicilliformis. At right is detail of cell shape.
Green Seaweeds | 55
Identifying Pacific Seaweeds
Branched Filaments
Acrosiphonia Green rope
Class Ulvophyceae Order Ulotrichales Family Ulotrichaceae
Number of Species
Of the 13 Acrosiphonia (Greek=tube-topped) species worldwide, three species are found in our area: A. duriuscula, A. coalita and A. arcta.
Description
Typically, the attached and branched plants form rope-like strands that result from hooked branches tangling the thread-like filaments together. Often these hooked filaments can be seen with the aid of a magnifying glass. More conspicuous forms may reach 40 cm (16 in) in length. This group of multi-nucleate plants (many nuclei per cell) has been associated with a ‘Codiolum’-like phase (see Urospora, p. 53).
Habitat & Distribution
Plants 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