The deep sea anglerfish is one of the most bizarre-looking fish in the sea. There are more than 200 species of anglerfish, most of which live in the dark depths of the Atlantic and Antarctic oceans. They are dark grey to dark brown in color, have huge heads and enormous crescent-shaped mouths filled with sharp, translucent teeth. Some angler fish can be quite large, reaching 3.3 feet (1 meter) in length. Most however are significantly smaller, often less than a foot. It can weigh up to 110 lbs (50 kg).

The most distinctive feature in female anglerfish is a piece of dorsal spine that protrudes above their mouths like a fishing pole. Their mouths are so big and their bodies so pliable, they can actually swallow prey up to twice their own size.
The male is significantly smaller than the female. When a male angler matures, its digestive system degenerates, making it impossible for it to feed on its own. It must now find a female or die of starvation. The male angler has small hook teeth, which it uses to attach itself to the female. Once he bites into her skin, he releases an enzyme that dissolves the skin of his mouth and that of her body. The two become fused together and their blood vessels join as one. The male will spend the rest of its life joined to the female like a parasite, getting all of his nourishment from her body. A female will carry six or more males on her body.

The deep sea anglerfish has a round body that resembles a basketball. It has a very large mouth with sharp, fang-like teeth. Due to its wide, round body, it cannot swim very fast. Its skin is specially adapted to reflect blue light. The anglerfish's lighted lure glows with the help of millions of bioluminescent bacteria. Since nearly all light emitted from bioluminescent creatures is blue, the anglerfish can be nearly invisible to other deep sea animals.

The anglerfish uses its illuminated lure as its hunts for prey. This specialized spine is highly flexible and can be moved in any direction. The anglerfish remains completely motionless, waving its lure back and forth like a fishing pole. When the prey fish gets close enough, the angler snaps it up with its powerful jaws and swallows it whole. The sharp teeth of the angler are angled inwards, which helps to prevent the prey from escaping.