Eel

Eel is an enemy found in Jolly roger bay. In the 1st quest, the eel will be hiding in the sunken ship. Swim near it to get it out. In "Can the eel come out to play?", it will be hiding in its home, waiting for mario to come near him. When you do so, it will lunge at you and then come out and swim in a circle. There is a Power star stuck to its tail. Touch it and it will go near its house. Grab it and the quest ends. In quest 3 4 5 and 6, it will be constantly swimming in circles.