Top 100 species: Earthworms come out above humans and dinosaurs

The humble earthworm has been ranked above dinosaurs, bacteria and even mankind in a new league table of the most successful 100 species on Earth.
Louise Gray, The Telegraph 3 Oct 09;

Traditionally those animals and plants that have most benefited humans have been considered the most important to science.

However, a new book looks at the whole history of the Earth and all its life forms to judge which are most successful.

The top 100 includes sea squirts, the honey bee, black pepper and dung beetles. It also includes unpleasant but powerful life forms such as the HIV virus, mosquitoes, slime mould and herpes.

Christopher Lloyd, the author of the book, said he wanted to show the evolution of life in a "jargon free way" from loose strands of amoeba billions of years ago right up to elephants and the latest strain of influenza.

To rank species he judged each life form on longevity, the impact it has had on the planet, evolutionary success and geographical spread.

The earthworm, which has been around for 600 million years, is spread across the earth and provides a basic biological model for many other species including humans came out top.

Human beings lose points for our relatively recent arrival to the evolutionary story, coming in at number six. Algae, which is responsible for providing the oxygen upon which other species rely, comes in second followed by three forms of bacteria that also make it possible for other life forms to thrive

Mr Lloyd pointed out that earthworms have survived five extinction events and make human civilisation possible by ploughing and fertilising the soil.

"There is no reason that humans should be top of the list just because we think we are the most powerful. We have only been here for about 160,000 years compared to 600 million years for the direct ancestor of earthworms and our impact on the environment is relatively recent," he said.

"It is a vital message to get across – to see the history of life in the context of science and biology as well as human culture – because we depend on earthworms and all other species on the list for our own lives and need to work with nature in future."

What on Earth Evolved? has been published to coincide with the 150th anniversary of Charles Darwin's Origin of the Species.

The great biologist also admired the earthworm writing: "It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures."

The top 10 species are:

1. Earthworms

2. Algae

3. Cyanobacteria

4. Rhizobia

5. Lactobacillus

6. Homo sapiens

7. Stony corals

8. Yeast

9. Influenza

10. Penicillium