Bioluminescence


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This week’s blog comes from Rhiannon Laubach. Rhiannon has an interested in the environment, environmental education and history. She studied environmental science and ecological management at University. She enjoy bird watching, botany and photography.

lichenBioluminescence is a fascinating ability that some organisms have; it is a naturally occurring process that allows them to produce light. The light is created by a chemical reaction. The reaction is very efficient so it produces very little heat. Molecules known as luciferins are catalyzed by an enzyme known as luciferase; the molecule is now in a high energy form.  When it relaxes, it releases a photon of visible light. Most organisms that have this ability are found in the world’s oceans, but a minority are found on land such as fireflies and even some lichens.

There are a number of different reasons why organisms have this ability such as a way of protecting themselves, attracting a mate or as part of a hunting strategy.

Dinoflagellates are small single cell plants that float in the water column; they use bioluminescence as a defence mechanism. At night they float to the top of the water column. The dinoflagellates flash their light when they are disturbed. The disturbance could be a fish trying to eat them or something more mundane like a wave .This light flash has two functions it distracts the predator from the dinoflagellates and could make the predator visible to larger animals that could prey on it. So, it could be forced to leave the area.

The deep ocean is in constant darkness shrimp species knowns as Systellaspis debilis uses symbiotic bioluminescent bacteria as a defence mechanism. The shrimp squirts the bacteria at its attacker, their bright flash allow disorientates the attacker and gives the shrimp enough time to escape (hopefully!).

The cookie-cutter shark use bioluminescence as part of a hunting strategy. This shark is relatively small (adults are about 2 foot long) and uses bioluminescence as part of it’s hunting strategy that allows it to take prey larger than its self. The shark’s underside is covered with organs that produce bioluminescence, this helps to camouflage the shark. During the day the shark swims near the surface. However, not the entire shark is covered with the light producing organs, so it actually creates a much smaller silhouette compared to its actual size. This will attract larger predators to the shark, when they move into attack the shark twists round quickly before taking a cookie shaped bite out of the larger fish.

Some fish uses bioluminescence as way of attracting prey, deep sea fish such as angler fish, have bioluminescent bait that is attached to its head; it looks a bit like a fishing rod. This light attracts unsuspecting fish to it, which are quickly eaten by the angler fish.

On land, male fire flies can flash their light to attract mates. They can vary the intensity and frequency of flashes. Females are attracted towards the higher intensity and frequency as this indicates that the males are in better condition.

Akilesh, S. (2000). Bioluminescence Natures Bright Idea. Available: http://dujs.dartmouth.edu/2000S/06-Biolumen.pdf. Last accessed 29th Jan. 2015.

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