The siphonophore Praya dubia is considered one of the longest animals on Earth. In the polygastric phase, it consists of a pair of expansive, smooth, opposing, huge, elongated nectophores that are similar. The hydroecium appears as a deep groove extending from the apex to below the level of the nectosac’s ostium, bordered by two lateral flaps. It is partially closed above by a small gelatinous flap and completely enclosed below by lateral flaps. The pedicular canal is simple and unbranched. The somatocysts have three main branches, with thick, opaque white strands clearly visible within the transparent mesoglea. The median branch lies in the mid-longitudinal region, running anteriorly almost up to the apex of the nectophore, and then dividing into two lateral branches that extend to the nectophore’s lateral edges.