Monterey Bay Aquarium Research Institute
Marine Botany

    Habitat and Distribution

    Prionitis at home in a tide poolTide Pool Prionitis

       The suspect should be easy to locate. Prionitis lanceolata is the Joe Schmoe of the shores and can be found almost everywhere. The ones above are sitting pretty in a shallow tide pool at low tide, growing on some rocks, as P. lanceolata is wont to do. It has been sighted in the intertidal (as high as +1.5 feet above mean lower low water) as well as the subtidal (up to 60 feet deep). Its range extends from British Columbia, Canada to southern California. If spotted outside this range, please report, as this may mean the subject is on the run.

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    Morphological Variation

              To further its disguise, Prionitis lanceolata takes on a wide variety of shapes and sizes, depending on where it is growing. When lurking in the subtidal, it is a reddish-brown color and larger but with fewer proliferations. Subtidally, it has been observed to be 20-80 cm tall with only one or two stipes* growing from a holdfast. The number of branches is likewise reduced with long intervals between branching.
              As it gets higher in the intertidal zone, P. lanceolata generally becomes smaller but more densely branched. In the mid- to low intertidal, it is a reddish color and 20-35 cm tall with multiple stipes emerging from one holdfast. It branches more frequently than those in the subtidal and the ends of blades are usually furcate, or divided in two. In the high intertidal, it can be light red to brown and is even smaller (3-15 cm tall) with a very dense branching pattern.
              One last category that was described was those individuals living in the intertidal by a sewage outfall. They are purplish to brownish-black. Their branching is very irregular, with branching occurring on all surfaces. The thallus* is also swollen.

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    Created by Alice Chiu, 2003. Images may be used with permission.