Complex sentence: It is further distinguished by the presence of a taller spiny "crest" on its back with spines as long as running from the nape of the neck to the base of its tail, and its ability to rapidly change color from green to black when aroused.
Split into simpler sentences: It is further distinguished by the presence of a taller spiny "crest" on its back with spines as long as running from the nape of the neck to the base of its tail. The Fiji crested iguana has an ability to rapidly change color from green to black when aroused.