Where did Yoshi got his curly hair?

As you all know, Yoshi was born with lots of hair, now getting longer (I even thought of taking him with me to haircut today....). But most interesting part is his hair turns to natural curl everytime after wet... (this is a photo of him smiling in the bathtub, 5 sec before he gave us a huge "suprise" which lead to me and grandma's loud scream for help.....yes, he pooped in the bathtub....)