mammals
Yes , mammals are part of chordate groups . Class mammalia is included in group Tetrapoda and they are part of vertebrata which is sub phylum of Chordata .
hagfish is the only chordate that lacks a backbone
It doesn't. It's not even a chordate. Look at Cnidaria instead.
chordate phylum
that
Chordates are that group of animals having some form of a spinal column (which include the vertebrates).
Being 'chordate' means that the animal has a backbone.
I do not know to be honest, sorry.
no
Chordate
Chordate
Chordate