HOLDFAST MOVEMENT IN THE HYDROID CORYMORPHA PALMA: MECHANISM OF ELONGATION

¹ Department of Organismic Biology, University of California, Irvine, California 92664

1. Stolon-like holdfasts in the hydroid Corymorpha palma elongate along a substratum. This occurs rapidly and without an increase in cell number.

2. Holdfast elongation represents tissue stretching by the holdfast tip, which actively moves across the substratum. Holdfast tips show the migratory capacity even after they are severed from the trailing tissue. Their movement apparently is due to proximally directed waves in the tissue surface which push against the substratum.

3. Holdfast elongation thus represents an example of patterned morphogenesis which is not dependent upon cell proliferation. It is possible that typical hydrozoan stolons similarly elongate at least partly by means of terminal behavior, rather than by cell proliferation at the tip.