The oxygen we breathe comes from trees

The oceans are responsible for 70% of the oxygen that we breathe, and it mostly comes from phytoplankton 

While studying in school, we are taught that trees and plants take in carbon dioxide and give out oxygen. This oxygen is taken in by human, animals, birds, and other living organisms during respiration. So, it is assumed that trees and plants are the primary sources of oxygen on Earth. But according to science, this information is false. About 70% of oxygen found on Earth is provided by phytoplanktons in the ocean.Phytoplankton, or micro algae, are microscopic plants living in the ocean that contain chlorophyll and perform photosynthesis just like trees. Through photosynthesis, plankton gives out oxygen and takes in carbon dioxide. Phytoplankton also help in transferring carbon dioxide from the atmosphere into the ocean. Each year, phytoplankton transfer about 10 gigatons of carbon dioxide from the atmosphere into the ocean.