Life Without Light (Video)
Written by the BBCEarth team
Without sunlight, life on Earth would not exist. Every organism that has evolved on the surface of our planet has received energy either directly or indirectly from the sun.
Even creatures that lie at the depths of our oceans and have never felt the sun’s rays, not only survive but can actually flourish thanks to solar energy. 120 kilometres off of the Californian coast at a depth of 1,250m a diverse ecosystem is thriving in the darkness. Rising up 2280 metres from the seafloor, the Davidson Seamount, an underwater mountain, is an ‘oasis in the deep.’
Thought to have formed between 9 and 15 million years ago from volcanic eruptions, the ancient seamount is home to some of the slowest growing communities in the ocean. For example Paragorgia arborea, more commonly known as pink bubblegum coral, grows to over three metres in height and is over 100 years old.
But how has this seamount managed to sustain more biodiversity with a higher species count than that of the neighboring seafloor?
Its elevated position creates complex current patterns which influences what can live there. The mountain provides a place for species, such as coral, to attach to it which in turn provide food and shelter for other species. Due to these unique conditions seamounts demonstrate a high degree of endemism. Much of the deep sea is fed by the “compost” or “marine snow” from the upper sunlit portions of the sea. As plants and animals at the surface die and decay, they fall toward the sea floor. This snow provides carbon and nitrogen to feed many of the scavengers in the deep sea; testament to the fact that the sun’s rays touch far beyond where they can be seen.
But what happens when there are no nutrient-rich currents to feed from? No organic material falling down from above? Or when the extreme conditions make life almost impossible?
Over the last 30 years, researchers have discovered deep sea-ecosystems that live independently of the sun’s energy. These communities survive by utilising chemical rather than solar energy. Deep-sea organisms such as mussels, shrimps and squat lobsters host methane fixing bacteria, which convert the chemical energy from methane bubbling out of the sea bed into nutrients.
In this remarkable video from BBC Earth’s Life series, David Attenborough shows us exactly how an assumed barren seabed, became an abundant source of food and life.
These extremophiles have found a way to survive by utilizing the energy source which is most abundant to them, begging the question: If life has been found to flourish in even the darkest, saltiest, most inhospitable places where might we find it next?
The search continues…
This post was originally published by BBCEarth.
Photo from BBCEarth