Physalia utriculus (Bluebottle (Indo-Pacific form))

Physalia utriculus, also called blue bottle or Indo-Pacific Portugese man-of-war, is a marine Hydrozoan of the order Siphonophora found in the Indian and Pacific Oceans. 

A gas filled bladder allows it to floar on the surface, propeeld by currents, tides and by a sail at the top of the bladder.

A single long tentacle of venomous cnidoctyes. hanging below the float, provides the animal with a means of capturing prey.