The capiri split from it's ancestor. The capiri developed three spikes on its back (made of hard skin) and its sail grew in between them.
They now use their sail to communicate instead of their skin. They can still change the color on their skin but they only use it to make spots that shows who the individual is.
They have many combinations of color and shapes they show to each other in different situations and each herd uses slightly different symbols.
The advantage of using the sail as a communication method is because it's better to see and because the sun can shine through it so it's very clear