The massive capiri has split from the wading capiri. Due to the predation of the waxfaces, the wading capiris on the island were forced to adapt. Some populations in the south shrunk in order to hide under the vegetation, while the population in the north grew to defend against the waxfaces, giving rise to the massive capiri. They are so large the waxfaces have no way of attacking a fully grown adult. The young grow fast after hatching, adding about 7 lbs a day to their bodies. Their tail bones are thick while their skulls are hollow in order to prevent their bodies from becoming front heavy and tipping over.