What constitutes the primordium of the adult parasite [ Rhizocephala ]? What can be injected through the narrow opening of the dart's hypodermic device? ...Imagine going through such complexity as nauplius, cyprid, and kentrogon - and then paring yourself down to just a few cells for a quick and hazardous transition to the adult stage. What a minimal bridge at such a crucial transition! ...But other species have achieved the ultimate reduction to a single cell! The dart injects into the host's interior, and the two parts of the life cyle maintain their indispensable continuity by an absolutely minimal connection - as though, the rhizocephalan life cycle, nature has inserted a stage analogous to the fertilized egg that establishes minimal connection generations in ordinary sexual organisms.
Stephen Jay Gould