Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: The distribution of species and morphs of the rocky intertidal barnacles Chthamalus fissus and C. dalli (Cirripedia: Chthamalidae) in various habitats
Student Author(s): Wu, Norbert M.
Faculty Advisor(s): Baxter, Charles
Pages: 19
Location: Final Papers Biology 175H
Date: June 1982
Keywords: upper intertidal
splash zone
Abstract: The high intertidal acorn barnacles Chthamalus dalli and C. fissus both occur at Cabrillo Point. C. fissus occurs in two morphs: one has a narrow, slit-like aperture and the other has an oval orifice and is externally indistiguishable from C. dalli. Analysis of population samples found distinct patterns in the distribution of the species and morphs. These patterns applied to both micro- and macro-habitats. C. dalli was more abundant in the sites exposed to wave action while C. fissus dominated populations in protected habitats. The oval morph of C. fissus preferred sunny areas, whereas the slit form preferred moist, shaded environments. The slit and oval morphs of C. fissus develop their morphological traits at an early stage of development, and an argument is made for the genetic determination of the morphs of C. fissus.