( ( ( The characteristic ) ( that ( ( ( sets them ) apart ) ( from ( the invertebrates ) ) ) ) ) ( ( is ( ( the presence ) ( of ( ( a ( spinal column ) ) ( that ( ( is usually ) ( surrounded ( by ( a ( backbone ( or ( vertebral column ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN characteristic)) (SBAR (WHNP (WDT that)) (S (VP (VBZ sets) (NP (PRP them)) (PRT (RP apart)) (PP (IN from) (NP (DT the) (NNS invertebrates))))))) (VP (VBZ is) (NP (NP (DT the) (NN presence)) (PP (IN of) (NP (NP (DT a) (JJ spinal) (NN column)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (ADVP (RB usually)) (VP (VBN surrounded) (PP (IN by) (NP (DT a) (NN backbone) (CC or) (NN vertebral) (NN column))))))))))) (. .)))
The characteristic that sets them apart from the invertebrates is the presence of a spinal column that is usually surrounded by a backbone or vertebral column.
(ROOT (S (NP (NNP Backbone)) (VP (VBZ is) (NP (NP (DT another) (NN name)) (PP (IN for) (NP (DT the) (JJ vertebral) (NN column))))) (. .)))
Backbone is another name for the vertebral column.