We rarely see these 15 species of strange deep-sea fish, and even more rarely get to see their insides. They look scary, but most are only dangerous to other creatures that live in the ocean depths. Shown here is the inner workings of the Pelican Eel, also known as the Umbrellamouth Gulper, which isn't an eel at all. The fish's jaws (at the bottom) are bigger than the rest of its body, and it can swallow fish larger than itself. See 15 such weird creatures at Environmental Graffiti. Link
(Image credit: Sandra J. Raredon, NMNH, Division of Fishes)