Background
Marcus was born in Berlin in a Jewish family.
Marcus was born in Berlin in a Jewish family.
In 1914, he published his first zoological work, but his studies were later delayed due to World War I, where he fighted as a soldier, and his second work was published only in 1919. By this time, he was already a professor at the University of Berlin. As an assistant to Karl Heider, Marcus became interested in Developmental Mechanics.
Later works were published in English and focused on several invertebrate groups, such as flatworms, annelids, tardigrades, onychophorans, nemertines, phoronids, gastropods, and pycnogonids.
With the rise of Nazism in Germany, Marcus was dismissed as an assistant to Heider in 1935 and moved to Brazil with his wife in 1936, where he started to teach zoology at the University of São Paulo.