Eudendrium racemosum (Gmelin, 1791) (Anthomedusae, Eudendriidae) is a very common hydroid in the Mediterranean. I occurs in a few meters depth. The colony can reaches heights of 3-10 cm. The present colony is growing on the ascidian Microcosmos sulcatus, of which the striated in- and exhalent siphonsare visible.