Bioluminescence in Krill and Other Deep Sea Creatures for Kids!

Bioluminescence in Krill and Other Deep Sea Creatures for Kids!

We can derive a basic understanding of the word “bioluminescence” by breaking it down into two parts. “Bio” refers to a living thing while “luminescence” is an emission of light. Put together, we get living creatures that create and emit light! It sounds astonishing but perhaps you might have seen an example of this in your own life. For example, fireflies and glowworms are among two of the best known bioluminescent creatures. While we don’t often see bioluminescence on land, in exists in large numbers within the depths of the ocean. For example, many scuba divers know that waving their limbs about in the water during a dark night dive will cause scores of tiny plankton to light up all around them, as if by magic! However, there is a very valid scientific explanation behind these pretty sights. All of these creatures biologically produce an enzyme called luciferase as well as a pigment called luciferin. When the pigment combines with oxygen, it produces light, while the enzyme accelerates this chemical reaction. Read on to discover more about the fascinating world of underwater bioluminescence!


Krill are very tiny creatures that resemble shrimp. They have a hard outer shell that is mostly transparent. Krill are so small that they are typically at the bottom of the ocean’s food chain. There is some debate as to whether krill produce luciferin themselves, but some studies have shown that they merely ingest it while feeding. While scientists have not agreed on a firm answer as to the purpose of the krill’s bioluminescence, some guess that it might be to attract a mate or to help camouflage in brightly lit areas.

Bioluminescent Squid

Although there are several different types of squid, many of them share bioluminescence as a common trait. Often, they have photophores on their bodies, which are cells that produce light. These photophores help the squid to startle any potential predators by emitting bright flashes of light. Other types of luminescence employed by squid are bioluminescent secretions (think of a glow-in-the-dark version of octopus ink) and glowing bacteria that cling to the squid’s body.

Bermuda Fireworms

Bermuda fireworms (also known as Bermuda glow worms) are tiny creatures that live in the ocean. However, following a full moon, the female fireworms head to the surface and use their bioluminescent abilities to attract the males. The males themselves also produce brief flashes of light as they swim to mate with the females. Many observers have compared this sight to a swarm of fireflies in the water. It is such a remarkable spectacle that today many cruises are organized in Bermuda simply to allow tourists and visitors a chance to view the fireworms in the water.


While most people might associate anglerfish with the terrifying deep sea creature with a sort of lantern attached to its head as made famous in the movie, Finding Nemo, the description is actually not that far off from reality. Anglerfish do have sharp, spiky teeth and a series of spines on the outside of their bodies. In addition, they have a long and very prominent spike that protrudes from the top of their heads. At the end of this spike is a piece of flesh inhabited by large amounts of bioluminescent bacteria. Smaller fish are attracted by this strange glow in an otherwise pitch dark environment, and as they come closer to investigate, the anglerfish quickly snaps them up as food.

Clusterwink Snail

At first glance, clusterwink snails might seem a bit of a conundrum. The snail’s body is bioluminescent and despite the shell being completely opaque, it still glows in the dark! The answer behind this strange marine party trick is simply that the shell is used to reflect the internal light. When viewed in daylight, the shell appears thick and yellow, while at night it turns a neon green. The reason behind this is simply to scare off possible predators.


Atolla are another type of jellyfish that usually exist in very deep waters. They have a round, dome shape with several tentacles at the edges. During its feeding, the atolla consumes large amounts of zooplankton (small marine creatures) which are bioluminescent. When the atolla is threatened or attacked, it can trigger an internal bioluminescent display. Since its coloration typically ranges from red to purple to black, it displays these colors when the internal light is filtered through the pigmentation.


Tomopteris is a type of small marine worm. It is comprised of many horizontal segments, with the body ending in a tail. Light is emitted through the claw-like appendages that are found at the end of each segment on its body. Unlike most other bioluminescent marine creatures that normally emit light in hues of green and blue, the tomopteris emits light that is yellow.

Vampire Squid

Vampire squid certainly sound quite dramatic and their official name, Vampyroteuthis Infernalis, is even more sinister when translated: “Vampire Squid from Hell.” What did this creature do to deserve such a name? A large part of its unfortunate moniker is derived from the squid’s physical appearance. Its coloration ranges from red to a deep black and the body is covered with a layer of skin (black on the inner side) that resembles a cloak. The spiked wing-like fins and red eyes only add to its alarming appearance. More importantly, the entire body is coated in the light cells called photophores. Vampire squids are able to control the strength and duration of light that they emit to a very fine degree.

Colonial Jelly

Another name for the colonial jelly is colonial siphonophores. They are a type of invertebrates that live within the ocean. Since the siphonophores often cluster together, they are sometimes mistaken for jellyfish. The Portugese Man ‘o War is one of the very well known examples of a colonial jelly. As with other siphonophores, the Portuguese Man ‘o War is actually several creatures who cling together and thus travel together. It is thought that most colonial jellies employ bioluminescence as a method of detecting and attracting prey.

Another oceanic phenomenon which is sometimes confused with bioluminescence is red tides. Red tides are in fact not caused by fish at all, but instead they are simply due to an overgrowth of red-colored algae. They have often been found in the Gulf of Mexico as well as other areas on the U.S. and Canadian coastlines. Red tides, also known as algal blooms, are actually quite dangerous because they release a large amount of toxins in the water that are fatal to fish and aquatic plants alike. Eating fish from a red tide area can also cause illness in humans and animals.

There are many more types of bioluminescence that can be found when exploring life underwater. Very often, these strange creatures evolve in this manner in order to adapt to the demanding conditions that exist at such extreme depths. When exploring or examining marine life, do so with caution and respect for nature.