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IS IT a mushroom? Is it a jellyfish? No, it鈥檚 Dendrogramma, a new animal so bizarre in appearance that it has defied attempts to place it in the vast animal kingdom.
The two mushroom-shaped species of Dendrogramma were dragged up from the seabed off south-east Australia in 1986 by Jean Just of the Natural History Museum of Denmark in Copenhagen, and his colleagues. They have only now been studied.
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They belong somewhere in the lowest branches of the animal evolutionary tree, perhaps related to jellyfish or another primitive group called the comb jellies. But unlike jellyfish, Dendrogramma lacks stinging tentacles, and unlike comb jellies it is missing a comb of hairs.
According to Just, they most closely resemble the Ediacarans, a group of enigmatic organisms that most biologists think disappeared half a billion years ago, before the rise of animals (PLoS One, ).
鈥淭heir internal system shows a branching pattern similar to some of the Ediacaran fossils,鈥� says Just.
Others say the similarities with Ediacarans may be superficial. 鈥�Dendrogramma has a relatively simple shape and so any similarities with the external shape of Ediacaran taxa could well be coincidental,鈥� says at Queen鈥檚 University in Kingston, Ontario, Canada, who studies Ediacaran fossils.
DNA analysis might help to settle the matter, but will require new specimens. The chemicals used to preserve the animals have rendered their DNA unsuitable for study.
This article appeared in print under the headline 鈥淲eird creatures may be relics from dawn of animal life鈥�
