BBC News Online: Sci/Tech

Double-headed creature revealed

The creature is a primitive aquatic animal called a hydra.

The researchers believe it is the first step towards understanding the early stages of animal development.

The double-headed hydra was treated with a naturally occurring signalling substance. After five days, a graft of cells grew to form its second head.

The donor tissue contained fluorescent latex beads that gave the hydra's extra head a greenish glow.

Simple animal

The hydra is the first animal organism to have evolved a neural network.

Little more than a blob of cells, it lives in freshwater and uses tentacles to feed itself.

The work was carried out by researchers at the Zoological Institute, University of Jena, Germany.

The team believes the finding could help scientists understand what controls tissue development in higher animals, such as flies, worms and mammals.

The research is published in the journal Genes and Development.