Astronomers continue in their quest to discover alien life forms in the cosmos, but naturalists suggest that they should look closer to home as there is still a host of undiscovered species lurking on our own planet.
This month a species that has defied classification for thirty years has finally been named by scientists, though they are still no further forward in determining what they are.
The weird species, described for the first time recently in the journal PLOS ONE, poses the question of how much we really know about life on this planet.
The peculiar, mushroom-shaped animals were discovered in a deep subterranean world off the coast of south-east Australia at a depth of 400 and 1000 metres (0.2 – 0.6 miles). Initially, scientists were unable to grace the intriguing new creatures with a title or genus, but have finally ventured to name them Dendrogramma, and have established a new family which will be known as Dendrogrammatidae.
The mind-boggling new organisams, described as "multicellular, non-bilaterian, mesogleal animals with some bilateral aspects," are believed to be totally unique and cannot be classified to any existing animal group. They are around one inch (two centimeters)in length, are translucent and resemble a chanterelle mushroom in shape. Beyond that, no comparison can be made to any other living creature on the planet, say scientists.
"It’s a very interesting surprise, and it poses lots and lots of questions," says Simon Conway Morris, a biologist at the U.K.’s University of Cambridge who studies early animal evolution.
The new animals did have certain similarities to some long-extinct species, in particular to three fossils known as Albumares, Anfesta, and Rugoconites, causing scientists to wonder whether they were not a brand new type of creature, but rather surviving examples of fauna previously thought to have died out.
Whether or not they turn out to be lost species or a totally new variety of life, Leonid Moroz, a neurobiologist at the University of Florida’s Whitney Laboratory for Marine Bioscience in St. Augustine, said that their existence could "completely reshape the tree of life, and even our understanding of how animals evolved, how neurosystems evolved, how different tissues evolved," he says. "It can rewrite whole textbooks in zoology."
It is not yet known how the creatures live and survive, but biologists believe that they may drift through the ocean rather than attaching themselves to specific surfaces, though how they manage to propel themselves through the water is not clear. They have a simple oral opening, and it is suspected that they feed on microbes which become caught in mucus secretions around their mouths.
The animals were first discovered in 1986 by biologist and crustacean expert Jean Just, but to add to the thirty year old mystery, no other specimens of the unusual creatures have ever been found.
"It’s still amazing that no one has come back and said at least, ‘I’ve seen things like this,’ even if they haven’t published it," says Just, who is retired from the Natural History Museum of Denmark. "That’s exciting."
The original samples had to preserved in preserved in formalin and then ethanol, which made genetic analysis difficult, so Just and his colleagues live in hope that more specimens will be found .
Scientists are still not sure whether Dendrogramma should even be classified as animals, as one school of thought suggests that they could merely be fragments or larval stages of larger creatures.
If they are related to the ancient Albumares, Anfesta, and Rugoconites, then this does not help to decide their classification as these enigmatic organisms have puzzled biologists for decades due to their plant-like whirls and fronds, and shrubs. These life-forms are believed to have disappeared over 540 million years ago at the end of the Ediacaran period, and just prior toa time of rapid animal evolution known as the Cambrian explosion. Dendrogramma could have evolved a similar structure if it had been exposed to similar conditions, in a phenomenon called convergent evolution.
The general scientific consensus is still that the odd little beings are an independent new species, but in the absence of any further clarification, the jury is still out on their lineage and they could just as easily be descendants of some long-lost life forms.
"If this is true," commented Reinhardt Kristensen, an invertebrate zoologist at the University of Copenhagen, "then we have discovered animals which we’d expect to be extinct around 500 million years ago."