Today’s photographs and write-up are courtesy of Douglas Justice, UBC Botanical Garden’s Curator of Collections. This is the second in a series of at least four BPotD entries on algae.
Ulva intestinalis is pictured here attached to smooth basaltic rock in brackish water on MacKenzie Beach, just north of Pacific Rim National Park. This species is a common feature of tidepools around the world, where it is known variously as sea hair or (more appropriately) gut weed. An annual species, local beaches are littered with their bleached, dried-up stems as temperatures fall in the autumn.
Daniel adds: Note that many references will have this algae under the name Enteromorpha intestinalis (L.) Nees, e.g., DeCew’s Guide. For a long time, Enteromorpha was considered a distinct genus from Ulva, based mainly on its tubular growth form. The two genera have now been merged; see Hayden et al. 2003. Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera. (PDF) European Journal of Phycology. 38: 277-294.