Undertow

Undertow is a large tiger shark and Morgana's pet in the DTV sequel, The Little Mermaid II. He serves as the secondary antagonist in that sequel. He loves intimidating others with his size.

History
He is summoned by Morgana to eat the baby princess Melody, but King Triton turns him into a small, piranha-like fish, much to his chagrin. Undertow soon becomes obsessed with becoming a full-sized shark again, but Morgana's magic doesn't work, and he remains small throughout most of the film. He helps to deceive the older Melody into joining Morgana and getting Triton's trident.

When Morgana finally gets the trident, she turns Undertow back into his original size, at an opportune time. He is sent after the penguin/walrus duo, Tip and Dash, when they go to rescue Melody, and he attempts to eat them. Tip and Dash, however, manage to hold him off and steer him into

an ice wall that served as Melody's prison. Undertow shattered through the ice and was smashed against the rock wall behind it. All of his (very un-shark-like) teeth were broken, but it is unknown if he died or not.