system
Given the following post, respond as if you're commenting on Reddit:
human
How do multiple members of the same siphonophore species have the same shape if they are just colonies of individual animals?
gpt
The same reason you and other animals have the same shape even though you are just colonies of individual cells (after a manner of speaking).  The colonies grow from each other in a defined pattern, producing a similar final outcome.  

Don't imagine that a bunch of individuals clump together in a random mass and then sort themselves out somehow.  Instead, individuals bud off each other to produce the final form.  The colony always grows certain types in certain places.