Imagine your only source of communication on a dark Halloween night is with glow sticks? Well, imagine no more.
The ‘cold light’ of the ocean, is the phenomenon known as bioluminescence a form of chemiluminescence. Chemiluminescence uses a chemical reaction, which results in the formation of light. Halloween glow sticks, also known as cyalume sticks uses a form of chemiluminescence. This makes you think, products used in our everyday lives are using the mechanisms used by deep-sea organisms adapted to survive in that environment. Bioluminescence has been shown to be essential to the survival of those in the extreme environment – The Deep Sea.
Glow sticks use different dyes in order to produce different colours. The reaction that takes place is between the hydrogen peroxide solution and the diphenyl oxalate which is oxidised. An unstable compound is created, resulting in the production of CO2 whilst releasing energy. It is with the electrons of the dye which brings about an ‘excited state’ with the chemicals (refer to figure 1a). When the electrons lose their excess energy, they produce light. This is chemiluminescence.
It is due to chemical reactions, bioluminescence can exist. The chemical luciferin must be present within the body of the marine organisms. Marine organisms absorb oxygen, with this oxygen the chemical luciferin will react. Therefore, producing light. The mechanisms of glow sticks are similar to bioluminescence functions as they both use similar chemical reactions (chemiluminescence). They both use the same reactive compound called luciferin but bioluminescence differs as it occurs as part of a biological process in organisms. Different organisms use different luciferin compounds (as shown in figure 1b). A catalyst known as luciferase can also be present, resulting in an increase of speed with the reaction occurring. This is more useful for some than others, as some species need more control over their bioluminescence in order to light up immediately and regularly. For example, when searching for a mate or foraging for food. This depends on the chemistry and brain processes the marine organism possesses.
Wavelengths can also have an effect as it can dictate the colour and intensity of the light produced. For the most part, light present in the ocean is visible as a green-blue light (refer to figure 2), this being due to the wavelengths being shorter for these colours. Sunlight has a longer wavelength as it is travelling from the sun, therefore will come across as red light and doesn’t reach the deep sea. Due to this, some species will be seen as red in colour causing them to come across as ‘invisible’.
Eating, mating (communicating), defending, all would be difficult to do in pitch-black darkness, hence some deep-sea creatures have found their solution – Bioluminescence. As some deep sea marine organisms come across as red in colour making them invisible, their bioluminescence therefore allows specific deep-sea fish to observe and communicate with other fish as well as being advantageous for prey versus their predator.
Bioluminescence exhibits one very important characteristic; this is communication. Bioluminescence is very effective for communication in the ocean. In the deep sea, the transmitted sunlight is dim or absent completely, therefore an extreme environment where species must adapt to survive. Communicating in the dark? Difficult to do even for marine organisms (not all communicate audibly, body language is also needed), but some species have found that bioluminescence is an alternative way to communicate. Bioluminescence in the deep sea has been said to be “perhaps the most common form of communication found on our planet”. This was said in the following video:
The humpback anglerfish: Lure of a lifetime
The humpback anglerfish demonstrates how communication with others of its kind is possible with bioluminescence. This bathypelagic fish is black in colour and has few photophores present on its body. Photophores are organs that emit light, which appears as luminous spots. The humpback anglerfish uses its photophores to communicate and attract a mate. Being in the dark bathypelagic zone, bioluminescence draws attention to the organism emitting the light hence attracting a mate.
The humpback anglerfish also uses its bioluminescence to lure prey as well as mates. Let’s see how fishermen have adapted this idea to their own advantage; when fishing at night time, they use an item that glows with their bait, which in turn will lure fish (refer to figure 3). This idea works the same way in the deep sea and the humpback anglerfish shows this. With the use of bioluminescent bacteria called ‘photobacteria’, it allows for them to produce a light. This light is found just in front of their faces called the esca at the tip of their modified dorsal ray. Back to the fishermen analogy, it is like a “fishing rod”. This helps attract prey straight into their path where the prey is engulfed whole. The whole idea of grabbing attention brings us back to ‘glow sticks’ and how the light in a dark environment brings attention.
Flashlight fish: Warning off all enemies
Some fish need to continually give off light such as the humpback anglerfish and some flash their light on and off like the flashlight fish. The flashlight fish has an organ which produces light near its eyes, which is covered by a flap (resembling an eyelid) (refer to figure 4). Imagine a glow stick being covered by an arm, then becoming visible when the arm moves. In this case you would be unable to see the individual until the glow stick is visible again. Back to the flashlight fish, the flap of skin on the fish covers the light (refer to figure 4), which flashes on and off. Think of the Morse code but marine edition. This is a good use of communication as it allows for this fish to warn others to stay away.
Consequently, nowadays humans rely on technology to communicate and in the dark certain light sources are needed to be visible and in tern attract attention. Possessing a glow stick on a dark halloween is bound to attract attention like bioluminescence does. Not only do they both attract attention but glow sticks, a man made device, undergoes similar chemical reactions (chemiluminescence) to bioluminescence which is an evolutionary adaption. Many species have shown how it is significantly useful and necessary for survival. But lets imagine only having bioluminescence to communicate in the darkness of the deep sea; we have a choice where as in the deep sea they do not.