The animals of the class hydrozoa have both a polyp and medusa stage. Siphonophores are a type of hydrozoan with a float for buoyancy. Probably the most famous of these is the species physalia, the Portugese-man-of-war, which is a type of colonial siphonophore.

* Portugese-man-of-war

Pink-mouthed clustered hydroid (Tubularia crocea). They also form colonies.

BACK TO THE CNIDARIAN PAGE!