The term 'slithering sea creature' can be summarized as an EEL, which is a three-letter word. Eels are elongated fish that inhabit marine and freshwater environments. They are found in temperate and tropical waters around the world, and some species can even live in brackish water. Eels have slimy skin and can move quickly by undulating their bodies. They feed on small fish, crustaceans, and other invertebrates.