In Tubularia by a process of decapitation the hydranths may separate off and give rise to a separate individual, while the remainder of the body grows a new hydranth.
Nemopsidae, for the floating polyp Nemopsis, very similar to Tubularia in character; the medusa, on the other hand, is very similar to Hippocrene (Margelidae).
In Tubularia, on the other hand, the parenchymula develops into an actinula within the maternal tissues, and is then set free, creeps about for a time, and after fixing itself, changes into a polyp; hence in this case the planula-stage, as a free larva, is entirely suppressed.
The cleavage of the ovum follows two types, both seen in Tubularia (Brauer [3]).