The Encyclopedia of Walt Disney's Animated Characters: From Mickey Mouse to Hercules
Character Description of Flotsam and Jetsam from "The Little Mermaid" (1989)
Ursula's two hench-eels are certainly villainous-looking creatures: seen head-on they resemble not so much eels as gnarled old alligators, with their skewed eyes, crumpled-looking jaws and haphazard teeth. Their eyes glow luminously in the dark - indeed, they do more than that, for Ursula, gazing into a large air bubble that looks astonishingly like a crystal ball, is able to look through those eyes in order to spy on distant events. (This business of scrying - farseeing - has become very popular in recent Disney animated features: it plays an important part in the plot of Beauty and the Beast
The two eels (indistinguishable except for their eye colors) play a significant part in one of the movie's most effective minor pieces of animation. As Ursula is building up in the first few lines of her song "Poor Unfortunate Souls" they swim sinuously around her, reflecting the curves of her ample body, seeming to trail like the long scarves of an exotic dancer. The effect lasts for only a few seconds, but is very striking.
Although Flotsam and Jetsam have been clearly cast in the role of heavies, in truth they don't have very much "heavying" to do until the closing scenes of the movie and Ursula's titanic battle with Ariel and Eric. They meet their end when Ursula is preparing to incinerate Eric with her trident and Ariel attacks her, pulling her aim so wild so that instead the bolt fries the two eels, whose ashes trickle downwards and into the witch's vast hands. Oddly, for a moment we are persuaded that Ursula was actually fond of them, for she mourns: "Babies! My poor little poopsies!" But the grief passes rapidly and she wades back into the action.
The voices of Flotsam and Jetsam, supplied by Paddi Edwards, were electronically processed for additional effect. Presumably the implication is that they're electronic eels.