As opposed to what arthropods have, vertebrates have this internal framework
KS3 Bitesize 
Fish... [DOC] [TLE] Skeleton definitions - Defined Term [PAR] "skeleton": a supportive or protective structure or framework of an animal, a plant, 
... (exoskeleton) or internal (endoskeleton) support structure, against which the ... 
Vertebrates have a skeleton of bone or cartilage; arthropods have one made of... [DOC] [TLE] Origin of Vertebrates/Chapter III - Wikisource, the free online library [PAR] Nov 10, 2013 ...