Friday, April 09, 2010

Nowt so Queer as Earth Folks - 2010 update

When I first started blogging I ran several different blogs on a variety of subjects that interested me. Over time, I combined them and transferred all of the content to this one blog. I quite like the eclectic mix that has resulted. One of these early blogs was called Worlds of Possibility and it was a series of speculative essays (such as here, here, here or here), scientific articles (here or here) and even artists' impressions of what life could be like on other worlds (here or here). The subject of what life on other worlds could be like has fascinated me my whole life. Had I not been such an attention-seeking arty-fartist at school I would most definitely have tried to become a marine biologist. The sea is the most alien environment we can explore first hand and, let's face it, a lot of the stuff in the sea - especially deep sea - is about as alien as it comes.

Every so often, I post up some interesting little news stories that I hope you'll find as fascinating as I do. I have a couple of them here for you today. Before we start, however, I should point out that I have both of my humanoid feet firmly in the xenobiology camp. There are two distinct camps you see; astrobiology and xenobiology (within the broader category of xenoscience). The main difference is that astrobiologist tend to focus upon finding 'Goldilocks' worlds where conditions are 'just right' for life like that on Earth to have evolved. Xenoscience, meanwhile, is more adventurous. As Professor Jack Cohen describes it: ‘Instead of looking for carbon copies of Earth, we ought to be theorising about and looking for the different kinds of planets, and other potential habitats for life, that exist out there in the wide universe. ‘Exotic’ habitats should be seen not as obstacles, but as opportunities; instead of dismissing them with an airy wave of the hand and saying, ‘Obviously life couldn’t exist there’, we ought to be asking, ‘What would it have to be like if it did?’’' That kind of viewpoint appeals to my creative side and, every year that goes by, we find more and more forms of life here on Earth that simply don't conform to the rules we've always held to be rigid for life. Here's a great example, taken from today's Daily Telegraph; a complex life form that doesn't need oxygen:

'New species 'lives without oxygen'

The first animals that do not depend on oxygen to breathe and reproduce have been discovered by scientists on the bed of the Mediterranean Sea.

Three species of creature, which are only a millimetre long and resemble jellyfish encased in shells, were found 2.2 miles (3.5km) underwater on the ocean floor, 124 miles (200km) off the coast of Crete, in an area with almost no oxygen. The animals, named Loriciferans due to their protective layer, or lorica, were discovered by a team led by Roberto Danovaro from Marche Polytechnic University in Ancona, Italy. One of the species has been named Spinoloricus Cinzia, after Dr Danovaro's wife, while the other two, known as Rugiloricus and Pliciloricus, have yet to be formally named. They were found during three expeditions to find life in the sediment of L'Atlante basin in the Mediterranean, which took place over the course of a decade.

Professor Danovaro told BBC News bodies of multicellular animals had been found in sediment from a similarly oxygen-starved area of the Black Sea, but they were thought to have been carried there from adjacent oxygenated water. The species found in the latest expedition were alive, two of them containing eggs, and though they died on extraction the eggs were successfully incubated on the ship, and hatched in an oxygen-starved environment. The professor said: "It is a real mystery how these creatures are able to live without oxygen because until now we thought only bacteria could do this." Lisa Levin, of the Scripps Institution of Oceanography, wrote in the journal BMC Biology that further research into animals that can live without oxygen could help scientists examining the possibility of alien life existing on other planets.'
And here's another, a little older, taken from the Microscopy UK website:

'A Lobster's Microscopic Friend - Symbion pandora - a new life form and a new phylum.

Just before Christmas 1995, a new life form discovered by Danish biologists on the lips of the Norway lobster attracted world-wide media attention. Why? This topical article by Dave Walker describes and illustrates this "zoological highlight of the decade" using the biologists' published material and includes an exclusive photograph kindly supplied by the original researchers.
It is not that difficult to find a new species. Place an experienced botanist and zoologist in a poorly investigated area of the world such as virgin rainforest and leave them there for a while to study the fauna and flora. It is quite likely that a tiny beetle, fly or plant such as a moss may be found which is unidentifiable and is declared a new species. In fact it is believed that millions of species remain undiscovered. So why did the discovery of S.pandora excite not just the scientific community but attract media attention world-wide? For two main reasons.

Firstly, the organism was not discovered in the depths of a rain forest or an oceanic trench, but on the bristles surrounding the mouth of the Norway lobster Nephrops norvegicus which can be caught in the Kattegat Straits, a busy shipping lane between Sweden and Denmark. You've probably eaten the Norway lobster - as scampi and chips. Secondly, when a new animal species is discovered, no matter how unusual, it can normally be classified into a known group of creatures with the same body plan or phylum. Although there are 1.5 million plus known species in the world, they can all be classified into 35 or so phyla. These include the chordates (eg the vertebrates such as man), molluscs (snails) and arthropods (jointed limbed e.g. insects). However, S.pandora was so unusual that it could not be classified into any of the existing phyla, and a new one was suggested called Cycliophora.

The organism has a very complex life cycle, with a number of well-defined sessile (stationary) and free swimming stages with different morphologies. The largest and most illustrated phase is the feeding stage. The key features of this stage are as follows.

- typically 350 ┬Ám long
- attached by an adhesive disc to the lips of the lobster
- feeds using a mouth surrounded by a ring of cilia
- excretes via an anus next to the mouth ring
- the feeding stage continually produces inner buds which replace the feeding structures
- both asexual and sexual reproduction can occur

Pandora's sex life is so peculiar that scientists at the Natural History Museum, UK were left puzzled. A museum scientist was quoted as saying 'it is unlike anything we have seen before'. There was a debate whether Pandora had one penis or two, a fact eagerly announced by the popular press. The essential features of the sexual cycles are as follows. As well as sessile stages there are three free-swimming stages i.e.:

- a larva containing a new feeding stage
- dwarf males (size typically 84 um) which settle on feeding stages
- females which attach to the lobster, and subsequently degenerate producing larva which disperse.

All the free-swimming stages do not feed and are short-lived. Sexual reproduction is initiated when the lobster is near the end of its moult cycle. At this stage sexually mature feeding stages are found attached to the lobster's lips. The asexual aspect of the life cycle explains why large populations of feeding stages with no mature sexual stages have been found on lobsters.

Cycliophora, in which S.pandora has been placed, is thought to have affinities to the phyla Entoprocta and Ectoprocta. The Ectoprocta are also known as the bryozoans or moss animals. Bryozoans are microscopic invertebrates that can form beautiful colonies which are often attached to rocks and plants in both fresh and seawater. The bryozoans reproduce asexually by a budding process similar to that of Pandora.'

You see my fascination? If we have stuff like this right here on Earth, what chance is there of little green men ... or indeed anything even vaguely humanoid elsewhere?

Nature is far more bizarrely inventive than any of us petty humans ever believed possible.

1 comment:

Winifred said...

Well beam me up Scotty! Yes it's very bizarre.