Christian Andreas Victor Hensen (10 February 1835 – 5 April 1924) was a German

zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and d ...

and marine biologist (

planktology Planktology is the study of plankton, various small drifting plants, animals and microorganisms that inhabit bodies of water. Planktology topics include primary production, energy flow and the carbon cycle. Plankton drive the "biological pump", ...

). He coined the term ''

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

'' and laid the foundation for

biological oceanography Biological oceanography is the study of how organisms affect and are affected by the physics, chemistry, and geology of the oceanographic system. Biological oceanography may also be referred to as ocean ecology, in which the root word of ecolo ...

and quantitative studies.

Family

Hensen was born in the town of

Schleswig The Duchy of Schleswig ( da, Hertugdømmet Slesvig; german: Herzogtum Schleswig; nds, Hartogdom Sleswig; frr, Härtochduum Slaswik) was a duchy in Southern Jutland () covering the area between about 60 km (35 miles) north and 70 km ...

where his father ran a school for the deaf and dumb. His mother Henriette Caroline Amalie was the daughter of physician Carl Ferdinand Suadicani who founded an asylum in Schleswig. Hensen had eight sisters and five brothers including from his father's first marriage.

Education and work

Hensen went to school in Schleswig from 1845 to 1859 and then joined a grammar school in Glückstadt (Holstein) after which he joined to study medicine at the universities of

Würzburg Würzburg (; Main-Franconian: ) is a city in the region of Franconia in the north of the German state of Bavaria. Würzburg is the administrative seat of the ''Regierungsbezirk'' Lower Franconia. It spans the banks of the Main River. Würzburg ...

Berlin Berlin ( , ) is the capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within ci ...

(studying under Müller) and

Kiel Kiel () is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 246,243 (2021). Kiel lies approximately north of Hamburg. Due to its geographic location in the southeast of the Jutland ...

. In 1859, he received his doctorate in Kiel for a thesis on

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrica ...

and urinary secretions. He worked for a while at Kiel and in 1859 he became a lecturer in anatomy and histology. He became an associate professor in 1864, succeeding Peter Ludwig Panum. In 1867, he became a member of the

Prussian House of Representatives The Prussian House of Representatives (german: Preußisches Abgeordnetenhaus) was the lower chamber of the Landtag of Prussia (german: Preußischer Landtag), the parliament of Prussia from 1850 to 1918. Together with the upper house, the House of ...

to push towards studies of the ocean. Upon his initiative, the ''Royal

Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved by an ...

n Commission for the Exploration of the Oceans'' was founded. Hensen's students included Paul Höber, Hans Winterstein, and Hans Piper. He became a professor of

physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

in 1868 and worked at Kiel until 1891. During his time, he was head of five marine biological expeditions to the

Baltic Baltic may refer to: Peoples and languages * Baltic languages, a subfamily of Indo-European languages, including Lithuanian, Latvian and extinct Old Prussian *Balts (or Baltic peoples), ethnic groups speaking the Baltic languages and/or originati ...

and

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...

s, as well as the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

. He led an expedition in 1889 on the steamboat ''National'' from Kiel to southern

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...

in the north to as far as near the mouth of the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

Pará Pará is a state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest are the borders of Guyana ...

, Brazil in the south to study whether plankton can be found more in tropical waters than cold waters. Hensen also worked in

embryology Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, ''-logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos ...

and

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

examining the eye of cephalopods and the hearing organs of decapods. He discovered a structure in the

ear An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of ...

, the Hensen duct, also known as the Canal of Hensen. He also discovered Hensen's cells, Hensen's stripe, and two structures essential for the development of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s, the Hensen's node and Hensen's line. Hensen was for several years dean of the Faculty of Medicine and several times was rector of the University of Kiel. He was honorary doctor of Kiel, a member of the Leopoldine Academy, and a corresponding member of the Bavarian and Prussian academies of science.

Family and legacy

Hensen married Andrea Katharina Friederike Seestern-Pauly in 1870 and they had two sons and daughters. The ''RV VICTOR HENSEN'' is a research vessel named in his honor.

Works

* ''Zur Morphologie der Schnecke des Menschen und der Säugethiere'' (1863)

References

External links

Some text by Hensen
(in German and English)

(in German)
Correspondence between Darwin and Hensen
1835 births 1924 deaths People from Schleswig, Schleswig-Holstein Members of the Prussian House of Representatives People from the Duchy of Schleswig University of Würzburg alumni Humboldt University of Berlin alumni University of Kiel alumni Academic staff of the University of Kiel {{Germany-zoologist-stub