Biodiversity is the variety of genes, species & ecosystems shaped by billions of years of evolutionary history of life forms interacting with each other and their environment. Altered by human activity with lasting impacts at large scales that are difficult to predict. Nothing in biology makes sense except in the light of evolution . Darwin- descent with modification from common ancestors human impacts agricultural runoff invasive species. 1 = glochidia, 2=host dependent (can not complete life cycle without attaching to , Freshwater bivalves develop in 3 ways (bivalves 2 shells that are symmetrical: by producing veliger larvae(e. g dreissena polymphora)- zebra fish, by releasing fully developed young mussels(rare) 3. be passing early development as a parasitic stage on a host (e. g unionids) Adults are dieshious separate female and male forms, males release sperm in exhale side, female take in inhalant state.