Major fields within the life sciences used to be driven by curiosity and the qualitative analysis of species and organisms, their development, adaptation to changing conditions and mutual interplay. However, within the last 15 years life sciences have been truly revolutionized by technological advances that turn most biological disciplines into data-rich fields of research. The broad introduction of DNA sequencing technologies now allows the genetic analysis of whole ecosystems including the evaluation of the activities of different groups of organisms, from populations down to the individual cell, first illustrated by the metagenomic analysis of marine plankton. This development has been crucial for efforts such as the Census of Marine Life, or projects studying the human microbiome at unprecedented resolution. Using examples from our work in the Bermudas, the Red Sea and the Southwest Pacific, the interplay between quantitative and qualitative approaches in the modern life sciences will be illustrated.