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The extant graptolite <i>Rhabdopleura recondita</i> has been so far recorded only as inhabiting a bryozoan skeleton. Its larval settlement and metamorphosis are possible in the absence of a bryozoan zoarium, whereas further colony development may require that the larva is hidden inside the bryozoan host. This dependence may constrain the development of <i>R. recondita</i> tube and tubaria compared to the other <i>Rhabdopleura</i> species that develop without a host. We report here on larval settlement and metamorphosis in the absence/presence of a bryozoan host skeleton. We also make the first attempt to test the phenotypical response of <i>R. recondita</i> tubes and tubaria under variable hydrodynamic regimes in laboratory conditions. After 40 days, no significant variation was detected in the number or length of the newly formed tubes. These findings suggest that <i>R. recondita</i> eventually resides in a narrow velocity range and that tube and tubarium development is largely invariable.