Tuesday, 7 February 2012

The Oldest Animals On Earth

Sponges are some of the most primitive animals on Earth. They are little more than gooey clusters of cells held together by collagen fibres. The tiny tubes within its structure pump through sea water, filtering out the nutrients. Yet primitive living organisms are some of the most fascinating creatures as they give us a glimpse, like a living window back through time, of what the original members of the group were like. Sponges are so primitive that many scientists have theorised that they are a record of the first multicellular animals on Earth.

The 760 million year old fossils of Otavia antiqua,
the oldest multicellular animal on Earth
Palaeontologists excavating at the Namibia's Etosha National Park, believe that they have found fossils to support this popular theory. The team, led by Tony Prave, a geologist at the University of St Andrews, Scotland, found a series of tiny fossils in the 730 to 550 million year old rocks. The specimens were barely larger than a speck of dust, but powerful microscopes revealed the presence of a cavity at the centre, connected to the surface of the skin, by a series of small tubes through the layers of cells. 

They were given the name of Otavia antiqua. This sponge-like creature would have lived in deep, cold, oxygen-lacking waters, preying on algae. Their age of 760 million years old coincides with the predications made by molecular geneticists about the origins of multicellular animals. 'If one looks at the family tree and projects this backward to where you have what's called the stem group, the ancestor of all animals, then yes, this would be our great-great-great-great-great-great-great grandmother,' said Prave.