The first bite: The beginnings of predator-prey interactions on our planet

            In Where the Wild Things Were, Stolzenburg discusses the very first predator, which was most likely part of the “primordial soup” that generated multicellular organisms. I imagine during this time there were intense and viscous predator-prey interactions. Cells were being engulfed entirely (eating your neighbor whole!) or sucked up by some sort of apparatus or appendage. See this quote from Stolzenburg...

            “It was a natural step or two beyond that for predator and prey to add  spermlike tails and fluttering cilia of rudimentary self- propulsion, the first glimpses of the chase.”

One of the best (in my opinion) endosymbiotic diagrams 
from Keeling (2010) The endosymbiotic origin, diversification and fate of plastids 

            Scientists have discovered evidence of this predation.  Plastids contain relict prey membranes, still present and observed in most all plastid-bearing organisms. For example, early glaucophytes (a small group of algae) retain an extra membrane containing peptidoglycan (only found in the cell walls of bacteria). This wall is likely a remnant of the cyanobacteria that was preyed upon by early glaucophytes. It is fascinating that we are able to trace this sort of ancient predator-prey interaction.

           

            It is interesting to think about what sort of environmental pressures led to the first predation of one single celled organism upon another. Even further, what steps led to the permanent integration of this prey cell? What sorts of genes were transferred and how many millions of years did it take? Was the beginning of multicellularity ultimately driven by predator- prey interactions? I believe that scientists are just beginning to answer these questions with the amazing advances in genomics.

Didinium preying upon Paramecium (sciencephoto.com)

            Can you imagine what the first endosymbiotic event looked like? Are there any examples of predation that we can compare it to today? I imagine it looked something like one of the experiments that Stolzenburg describes with Didinium preying upon Paramecium. Gause, a microbiologist from the 30s, added Didinium to colonies of Paramecium and watched as the Didinium devoured every last Paramecium. He then added sediment to the bottom of the jar. Didinium again consumed most Paramecium, however a few were able to take refuge in the sediment. This simple experiment is interesting from a predator-prey perspective for several reasons. It shows how environment also plays a role in these interactions. Also, how predators drive niche specialization by causing prey to take refuge in different environments.

WATCH Didinium hunt and eat Paramecium.....

http://www.youtube.com/watch?v=HlHihxqqXOE

or...

http://www.youtube.com/watch?v=rZ7wv2LhynM