As opposed to what arthropods have, vertebrates have this internal framework
The arthropod fruit fly forms segments from a field of equivalent cells based on ... 
As such, organisms with a loosely defined metamerism, whether internal (as 
some... [DOC] [TLE] BBC - GCSE Bitesize Science - Endoskeletons and exoskeletons ... [PAR] Animals can have internal or external skeletons - while some do not have a 
skeleton at all.