Snorkel Snake

The Snorkel Snake, also called "Snorkle Fish" , is an enemy that apears in Yoshi's Story. It resembles a large, white serpentine creature with green spikes and a large fin for a tail. Its head is a large ball with red eyes, flippers, and a spout for a mouth. While identified as a snake in English and an eel in Japanese, it more closely resembles a giant, particularly due to the mouth.

The Snorkel Snake can be seen swimming on the world map of the Ocean, and is found in a single area of the level Lots O'Jelly Fish, where it waits for the Yoshi to swim nearby. When it spots them, it will swim in circles around them, attempting to enclose them within its spiky body; since Yoshis cannot throw eggs underwater, the Snorkel Snake is effectively invincible. However, its body is not long enough for it to make a complete circle, and there will always be an opening for the player to quickly swim out of.

Trivia

 * A similar enemy called Dragoneel appears in New Super Mario Bros. U, which also tries to encircle players with their bodies.