By guest reporter, Ella McKinnon (aged 12)

Have you ever seen pictures of glowing animals deep in the bottom of the sea and wondered, how do they glow? Well, this is called ‘Bioluminescence’ it is caused through a chemical reaction called the ‘Luciferin-Luciferase’ reaction. This chemical reaction happens inside the creature’s body, giving it a bright glow.

Land Bioluminescence
Although most bioluminescent organisms live in the ocean, there are a few exceptions, a commonly known bioluminescent creature is the firefly, fireflies have special bioluminescent muscles inside their abdomen. Fireflies can control their flickering glow, depending on how much oxygen they allow to get to their abdomen.

Another commonly known ‘land dwelling’ bioluminescence is the glow worm. Glow worms live on the walls and roofs of caves and produce a green bioluminescence which can only be seen when in almost complete darkness.

Bioluminescent Animal
The firefly squid is a deep ocean bioluminescent animal. The squid is covered in light producing organs called ‘Photophores’ the photophores allow the squid hide or conceal itself from predators below using a little something called “Counter illumination” the color of the squid matches the color of the ocean above it, so predators that are looking up from below cannot distinguish the difference between the squid and the blue ocean.

Firefly Squids. Image credit:

Image source:

Bioluminescence in the Ocean
A normal beach by day, but by night this beach at Jervis Bay on the south coast of NSW becomes a bioluminescent wonderland.

In the water of Jervis Bay lives bioluminescent algae, called Noctiluca. This algae is so small that thousands of them can fit into a single droplet of water.

Noctiluca is one of the most commonly occurring bioluminescent organisms in coastal regions around the world.

Noctiluca is not harmful to humans, but staying in large amounts of it can lead to skin irritation.

The name Noctiluca comes from the medieval Latin word ‘noctilūca’ meaning “something which shines in the night”.

So, if you ever see a firefly or a glowworm hanging on the roof of a cave, or a bright blue glow in the ocean, that’s bioluminescence!