I got an accidental shot of this last night, I have seen these before but can not find information on what it actually is. It looks like a tiny white shrimp or maybe a flea, it is so small it is hard to tell. It is just a bit smaller than a shrimp egg. It moves around kind of erratically and can swim short distances (a couple cm at best and then lands on the wood).
Jason Wechsler
Orange Eyed Blue Tiger Shrimp Blog (OEBT) 
Perhaps a Daphnia (water flea) or Gammarus? Both are common hitchhikers on plants and without any predator in the tank can survive. Both are crustaceans and where it is now is the adult size. As to getting rid of them, my only suggestion would be to introduce some microrasbora or ruby tetra and remove them after a week. They will probably have decimated the population by that time. They both can eat shrimplets, but I have kept them in planted tanks and still have a thriving colony of shrimp inside it. Both the creatures tend to stay in the upper water column while shrimplets stay lower, so any rasbora or tetra would likely eat the prior first.
Okay it is a Copepod Cyclopes Female carrying twin egg sacs.
http://www.micrographia.com/specbiol/crustac/copepo/cope0100.htm
Should be fine, I had those infesting my planted tank a month after I had set it up and it was weeks after adding a pair of guenthers nothos before they whiddled down their population.