Creatures That Glow in the Dark

One of nature's most fascinating oddities are creatures that are bioluminescent, meaning they produce and emit light. Many of these creatures exist deep in the ocean, and according to "Scientific American," the light they generate helps them locate food, attract mates and defend against predators. Bioluminescent creatures include lightning bugs, angler fish, ctenophores, firefly squid and reef fish.

  1. Lightning Bug

    • There are about 2,000 species of lightning bugs, also known as fireflies -- winged beetles that emit a green, yellow or pink chemically-produced light to attract mates or prey, depending on need. The glow is generated from the lower portion of a lightning bug's abdomen, and in the larvae stage, the creature is referred to as a glow worm.

    Angler Fish

    • Angler fish live in the depths of the sea, generally in areas where there's no light because the sun can't penetrate that far down. In those murky surroundings, angler fish produce light from a fishing-rod shaped fin that grows from their snout. The glowing tip of the fin is filled with bioluminescent bacteria, luring prey into the angler fish's mouth which features sharp, curved teeth that trap fish, squid and worms.

    Ctenophores

    • Also known as comb jellies, ctenophores are gelatinous sea organisms with small hairs that power them through the water. These creatures emit a powerful blue and green glow intended to repel predatory attacks. Sections of the ctenophore that are bitten off will continue to glow in a predator's digestive tract, causing the predator to become prey to bigger creatures attracted to the glow in its guts. Over generations, some predators have developed red and black pigments in their digestive tract that mask the glowing portions of recently consumed ctenophores.

    Firefly Squid

    • Native to Japan, the firefly squid is 2 inches in length and can zip through the water at a speed of up to 25 miles per hour. The firefly squid projects a blue and white illumination for the purpose of attracting a mate or for camouflage with the lights above the water's surface, making it difficult for predators to see them. The firefly squid can also squirt glowing mucus to distract a predator and attempt an escape.

    Reef Fish

    • Thirty-two species of reef fish were discovered in September 2008. They communicate with each other by emitting a red glow in the darkness of the sea. Reef fish live about 30 feet below the surface, and the red light they produce can be seen only at close range and under the sea. Scientists believe that in addition to communication, reef fish also use their light for mating.