The Hensen Net was invented by Christian Andreas Victor Hensen (February 10, 1835 - April 5, 1924) who was a German researcher considered by many to be the 'father' of Biological Oceanography. Hensen is credited with first using the term 'plankton', and the Hensen Net is one of several sampling devices he invented to help with sample collection. The Hensen Net has a 'reducing cone' forward of the net mouth, a simple closure system and a cod end collection device.
References:
Hensen, V., 1887. Uber die Bestimmung des Planktons oder des im Meere treibenden Materials an Pflanzen und Thieren. Berichte der Kommssion wissenschaftlichen Untersuchung der deutschen Meere in Kiel 5, pp. 1-107.
Hensen, V., 1895. Methodik der untersuchungen. Ergebnisse der Plankton-Expedition der Humbolt-Stiftung, Lipsius and Tischer, Kiel.