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Porphyra spp. (Purple laver)
Copyright © 2007 Jan Holmes
The 2006 seaweed key by Gabrielson et al list twenty-four species of Porphyra in our area. This is the seaweed nori sheets (sushi wrappers) are made of. It is a multi-billion dollar industry in Japan and the largest aquaculture business in the world. Louis Druhel notes in his book Pacific Seaweeds that Porphyra aquaculture and information about the life histories of Porphyra species in general have been made possible in large part by phycologists from our area. One researcher, Kathleen Drew, had a monument built in her honor in Japan which is prayed to daily by Shinto priests!
In the high and mid upper tidal area Porphyra can dominate the landscape as layers of dried out dark brownish green or black sheets covering rocks like shrink-wrap. Porphyra has a high tolerance for desiccation. When the tide rises and covers the dried out seaweed Porphyra re-hydrates to soft delicate transparent sheets. Species are one or two cell layers thick and sheets can reach lengths of over one meter (3 ft.). A tiny discoid holdfast anchors them to rocks, shells, and other seaweeds. Growth occurs throughout the blade. Some species can be lobed or ruffled around the edges, one common species, P perforata, may also bear small holes. Blade color varies among species from greenish blue to brown to pinkish red to black when dried. Porphyra spp. are high in vitamins, calcium and protein and have a high caloric content.
This
page was created by Jan Holmes on 1/20/07.
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