Catecholamines induce metamorphosis in the hydrozoan Halocordyle disticha but not in Hydractinia echinata.

Planula larvae of the marine hydroids Halocordyle disticha and Hydractinia echinata were treated with the catecholamines epinephrine, norepinephrine and dopamine, as well as with certain of their precursors and agonists. Norepinephrine, L-dopa, dopamine and the dopamine agonist ADTN at concentrations ranging from 0.1 to 0.