Sunday, August 28, 2011
Sunday Spinelessness - Little creatures that make a world
E.O. Wilson once described insects as "the little creatures that run the world". Wilson was presumably referring to the huge amounts of energy and mass that pass through insect bodies in terrestial ecosystems. There are, slightly puzzlingly, almost no insects in the sea but invertebrates still run marine ecosystems. In fact, invertebrates even create habitats in what would otherwise be unproductive waters.
We tend to think of the tropics as areas of great biological diversity - that's true for the land but less so in the ocean. The beautiful clear waters you see in tropical seas indicate a lack of nutrients and a corresponding lack of plankton. Without plankton, the normal marine food webs don't develop and, as a result, tropical seas are generally not very productive. But if you've been snorkling around a tropical island you'll know coral reefs are explosions of biolgical diversity. That's all because some coral animals can take advantage of the marginal conditions in tropical waters. These corals supplement the meager pickings that can filter from the water with energy trapped by a type of photosynthetic protozoa called zooxanthellae. In time these corals, with their protozoan helpers, can put down acres of calcium carbonate and create food and habitat for more and more animals. When those animals are anenomes, they can themselves form habitat for another animal. Like this anemone fish (or, as most people call them, NEMOS!!!) filmed earleir this year at Hideaway Island in Efate, Vanuatu:
As I vaguely recall from a misspent youth minoring in mycology, Eumycota that anastomose can form tubular hyphal systems with mobile nuclei and the structural framework (thallus) may persist longer than the genetic morphs that started them. That is, the actual genetic identity of a thallus may change with time as new spores (with new nuclei), germinate, join and take over a network. I think this would complicate estimating fungal diversity from DNA.
But then, I tend to think that species are abstractions, and fungal species so abstract they make my head hurt, especially when I'm having doubts that I correctly keyed out that sporocarp I just ate.
Now I know why I couldn't find this comment to respond to, it wound up on the wrong post! I didn't know about different fungi 'taking' over the infrastructure set up by others, I'll have to as Dave O. (how many Daves are there in this discussion!) next tiem I see him.
I think species are real, but sometimes very hard for us to find. And yeah fungi and plant species are much harder to think about than animals :)