( ( ( ( There ( ( is also ) ( ( another reason ) ( for ( bearing spines ) ) ) ) ) : ) ( it ( ( prevents or ) ( rather ( ( protects ( the ( cactus plant ) ) ) ( from ( being ( eaten ( by ( the ( desert animals ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (EX There)) (VP (VBZ is) (ADVP (RB also)) (NP (NP (DT another) (NN reason)) (PP (IN for) (NP (NN bearing) (NNS spines)))))) (: :) (S (NP (PRP it)) (VP (VP (VBZ prevents)) (CC or) (VP (ADVP (RB rather)) (VBZ protects) (NP (DT the) (NN cactus) (NN plant)) (PP (IN from) (S (VP (VBG being) (VP (VBN eaten) (PP (IN by) (NP (DT the) (NN desert) (NNS animals)))))))))) (. .)))
There is also another reason for bearing spines: it prevents or rather protects the cactus plant from being eaten by the desert animals.
(ROOT (S (NP (NP (DT The) (NNS spines)) (PP (IN of) (NP (DT a) (NN cactus)))) (VP (VBP help) (SBAR (S (NP (PRP it)) (VP (VBP survive) (SBAR (IN because) (S (NP (NNS spines)) (VP (VB protect) (NP (DT the) (NN cactus)) (PP (IN from) (NP (NNS animals)))))))))) (. .)))