“These creatures speak their love in the language of light” – Sara Lewis, Biologist
Where the light shines
The sun has disappeared, drawing a blanket of darkness gently over the horizon. The rich smell of earth explodes in my nostrils and I breathe deeply. The closer we get towards the Sand River, the louder the calming cadence of water over rocks becomes. As we make our way over the causeway, I switch off the vehicle. Entranced, we suddenly find ourselves in a sphere of light as hundreds of flashing fireflies dance their way across the night sky.
The natural phenomenon of bioluminescence has had biologists intrigued for generations, as early as the days of Aristotle. It refers to the manufacturing and radiation of light generated by a living organism and has evolved for a number of reasons ranging from a warning signal, attracting a mate, communication and mimicry. It was originally believed that the development of light in fireflies was to deter predators by warning them of their toxicity. However, it slowly developed into an intricate form of communication unique to these incredible beetles. So how do they manage to produce a ‘cool’ light, a feat no human has yet to emulate? Fireflies have two very important components: luciferase, which is an enzyme and luciferin, a pigment. The enzyme catalyses the oxidation of luciferin, which kicks off the ethereal light.
As Sara Lewis explains in her Tedtalk, the evolution of fireflies in particular has been powered by two main factors: natural selection as in basic survival and sexual selection, finding a mate and propagating genes. Although it varies greatly amongst the worldwide 2000 species of fireflies, the majority work on the line of the following: The female sees a flash of light, aims her light at that flash and returns a signal. This sparks a conversation in which the female will decide whether she wishes to continue the courtship. This is where things get incredibly fascinating. Lewis and her colleagues discovered that females are attracted to longer lasting flashes of light. During mating, the male does not only deposit sperm but also gives the female a nutrient filled package known as a nuptial gift which is crucial for the development of her eggs. This shows that the flashing communication is really the female trying to predict the size of the nuptial gift.
This sophisticated society is under threat mainly due to habitat loss and light pollution. With Earth Hour coming up this month, we felt that no other species would be more inspiring than the firefly due to their beautiful natural light.
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Written by: Andrea Campbell