align distribute

Arrakis,

You can draw both the basic fish ribs and the fish spine as stroked paths with the Width Tool suggested by Mike, and then you can use a copy of the fish spine directly as a Blend spine; you can hide the fish spine and show it when the fish ribs have been placed.

But the largest rib is number 5 out of 10, in other words not in the middle so you cannot make a Blend in one go between three objects.

Also, when you Blend>Replace Spine, the centres of the end objects will coincide with the ends of the spine, instead of having the ends of the fish spine extend past the ribs.

You can either cut off suitable and possibly different bits from the two Blend spine ends, so it becomes shorter than the fish spine, or you can add two surplus fish rib to the Blend (later to be deleted).

You can make two Blends, then Expand the Blends and move one set so the largest rib snaps to the other as suggested by Peter, then Ungroup and gather into one Group.

This will leave you with no blend, but you can make a temporary Blend with one step so you get temporary ribs between the real ones, then replace spine, then expand the Blend, then delete the temporary ribs (every second in betwen the real one) and the surplus end fish ribs.

That ought to give you the fish ribs placed orderly and following (the curve of) the fish spine.

Draw (curved) lines between the end points and center point of your vertebra, then replace spine for each...

A spine is a single line, not an object like you showed.

I'm sorry, maybe I'm just a little dense today, but I don't understand how the path below relates to the blends. In what way does the second image show anything curving evenly along the path?

These two blends, if you make the large arcs coincident

give you what's in your image

but seem unrelated to

Peter