The growth patterns of some hydroids that are obligate epiphytes of seagrass leaves

摘要: The growth patterns of the hydroids Campanularia asymrnetrica, Sertularia perpusilla and Algaophenia harpago on Mediterranean seagrass Posidonia oceanica, Laomedea angulata temperate Zostera marina, were examined. leaves grow from a basal meristem have short life which presents problems for these long-lived obligate epiphytes. Downward onto younger leaf tissue, shown by S. C. asymmetrica, reduces risk interspecific competition with other epiphytes, places substrates that survive longer than older distal close to young they can colonize stolon transfer. was found only areas leaves, possibly because progressive degeneration their most apical tissue. asymmetrica showed no such over length leaves. hydrorhizae small A. L. grew both upward downward along Both species abundant halves This distribution is considered be advantageous large branched are suited capturing planktonic prey, enhance probability colonizing neighbouring plants. Its disadvantages include reduced maintaining same plant an increased being eaten grazers.