Heart bug..

I was wondering around. Oh! I saw a doggy. Doggy, doggy, doggy! Picked up a bone, and after i right-clicked enough, and I tamed the wolf, I saw a bug on the hearts. I was next to a river..

How to remake:

1. Find a mob ( like cow, sheep, wolf, pig etc..)
2. Go next to a river. ( Any water source )
3. Tame it!

And the hearts are like "in water".
I can't tell it exactly, look at attachment