Champia parvula
Rhodophyta, Champiaceae
Authority: (C. Agardh) Harvey
Hawaiian name: limu `o`olu
Characteristic feature: Segmented hollow branches that resemble earthworms.
Description: Plants erect, tufted, moderately to strongly lubricous, to 6 cm tall, attached to rock or, if epiphytic, with prostrate axes and branches secondarily attached to substrata and making entangled mats to 15 cm across; axes to 2.5 mm diam., branches 0.5-1.5 mm diam., hollow, cylindrical to compressed, tapering toward apices; branching opposite or radial, or irregular on same plant, often at consistent 5-10 mm intervals; diaphragms mostly at intervals of 0.5-1.0 mm; 8-12 or more cells across cavity, depending on age of section examined. Tetrasporangia often numerous. Cystocarps conspicuous, to 1 mm diam., scattered on axes and longer or shorter branches; ostiole often prolonged.
Habitat: As single algal clumps in intertidal pools, on rocks, or epiphytic; in algal turfs on reef flats, often where surf is moderate to heavy; subtidal to 60 m. Often abundant in drift.
Hawaiian distribution: All main Hawaiian Islands, including the Northwestern Hawaiian Islands.
Other: Known as one-day limu or melting limu because fragmentation of the soft plants is rapid after immersion in the fresh water used to clean them. Often has a blue or green iridescence under water.