Sunday, February 6, 2011
As I mentioned in class if you remove the constraints of requiring lots of water and needing a large light capturing apparatus from photoautotrophs then we do see some mobile photoautotrophs - Euglena for example. Here they are having a party.
One way to lift this constraint for larger plants would be to be carnivorous - then they wouldn't need all that water or that light gathering apparatus. Although we colloquially call many plants 'carnivorous' they are not in fact heterotrophs because they still photosynthesize and use the animal bodies they capture for nitrogen, which is why we see the evolution of plant carnivory in nitrogen limited environments. They are still green, still need to be open to the atmosphere to take up carbon dioxide and still lose lots of water.
If a multicellular land plant did evolve towards true heterotrophy what would it look like? Thanks to the fertile imagination of British author John Wyndham we have the answer in the Triffids - and yes they would be mobile!
Although published in 1951 Wyndham's science fiction classic The Day of the Triffids is still a fantastic read. According to the director of the movie 28 days later, Danny Boyle, it was the opening sequence of The Day of the Triffids, in which a man wakes up in hospital to discover that a meteor shower has blinded his fellow countrymen, which first inspired Alex Garland to write the screenplay. As a bit of a triffid connoisseur I would rate the book and radio adaptation excellent, the BBC adaptations pretty good and the 1962 film version appallingly bad.
In England the book, and adaptations are so well known it is quite common for someone to refer to a large, somewhat creepy looking plant as 'triffid like'.