They intrigued Charles Darwin, helped to form the distinctive White Cliffs of Dover on the south coast of England and are thought to produce at least 50 per cent of the oxygen in the Earth's atmosphere. But marine plankton, which also contribute to the creation of fossil fuels, have until now been the unsung heroes of our planet.
A 16-minute film, narrated by Sir David Attenborough, aims to change this by bringing plankton science into the classroom. Created by Dr Richard Kirby, a scientist at the University of Plymouth in England, Ocean Drifters: a secret world beneath the waves tells the story of the most important natural cycle on Earth.
Kirby travelled the length and breadth of England over several years to capture images linking plankton to the landscape around us. The story begins in 1832, with a diary passage by Darwin relating how he examined plankton during his famous voyage of discovery. Describing the specimens he collected from the surface of the sea, Darwin wrote: "Many of these creatures so low in the scale of nature are most exquisite in their forms and rich colours - it creates a feeling of wonder that so much beauty should be apparently created for such little purpose."
Yet, after more than 150 years of study, it is now known that these organisms influence our lives in ways that most of us could never imagine. The film describes how plankton - which mainly consist of microscopic plants, small crustaceans and the eggs and larvae of larger animals - create much of the oxygen in the atmosphere, can encourage the formation of clouds in the sky and play a central role in the global carbon cycle.
But rising sea temperatures, as a result of climate change, are altering the abundance, distribution and seasonality of plankton, with potentially devastating long-term effects. The carbon found in oil and gas was slowly removed from the atmosphere by plankton over millions of years. It is now being returned to the atmosphere far faster than it was taken out.
"The plankton food web underpins the marine food chain, a web of life providing an annual harvest (for humans) of over 115 million tonnes of seafood," Kirby says. "They are also important climate regulators and have even helped to sculpt and create our environment. When you hold a piece of downland chalk in your hand, you are cradling the remnants of microscopic creatures that lived more than 100 million years ago.
"It has never been a more important time to pay attention to the unsung heroes of life on Earth that live at the sunlit surface of the sea."
Ocean Drifters: a secret world beneath the waves is supported by a book of the same name, published by Studio Cactus, and a website: www.oceandrifters.org.