This fact gave rise in ancient times to the false idea that the tapeworm originated from the union of these segments; and in modern times it has led to the view that the tapeworm is not a segmented organism (the monozoic view), but is a colony composed of the scolex which arises from the embryo and of the proglottides, which are asexually produced buds that, upon or before attaining their full size and maturity, become separated, grow, and, in some cases, live freely for a time, just as the segments of a strobilating jelly-fish grow, separate and become sexual individuals (the polyzoic view).
This idea originated in the discovery of a jelly-fish, gasteropods, and other organisms of a more or less marine type, and presenting some affinity with forms of Jurassic age.
The vast majority of jelly-fish float in the sea, with the exumbrella upwards, the subumbrella downwards.
In this way jelly-fish progress feebly by the pumping movements of the umbrella.
As the name jelly-fish implies, the mesogloea is greatly developed and abundant in quantity.