Thank you all,
I work for an education company. I´m in charge of reviewing books for students which are translated from Spanish. Some fellow teachers are traslating them and one of them used this term in a translation referring to invertebrates. The titles in Spanish have the intention to be catchy and in Spanish it says "Con y sin huesos" but the translation made "Bones and boneless" did not sound quite right to me. That's why I asked if it was correct. Somebody mentioned something which made sense to me: boneless sounds like invertebrates which bones have been removed. So as for the title, would it be better to change it for "Animals with Backbone and Animals without a Backbone?
Thanks again