August David Krohn was a Saint Petersburg

Saint Petersburg

Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...

 born zoologist of German origin. He was the son of Abraham Krohn, the founder of Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

's first brewery

Brewery

A brewery is a dedicated building for the making of beer, though beer can be made at home, and has been for much of beer's history. A company which makes beer is called either a brewery or a brewing company....

, who had left the island of Rügen

Rügen

Rügen is Germany's largest island. Located in the Baltic Sea, it is part of the Vorpommern-Rügen district of Mecklenburg-Vorpommern.- Geography :Rügen is located off the north-eastern coast of Germany in the Baltic Sea...

 to serve in the court of Catherine the Great

Catherine II of Russia

Catherine II, also known as Catherine the Great , Empress of Russia, was born in Stettin, Pomerania, Prussia on as Sophie Friederike Auguste von Anhalt-Zerbst-Dornburg...

. He was the uncle of the fennoman

Fennoman

The Fennomans were the most important political movement in the 19th century Grand Principality of Finland. They succeeded the fennophile interests of the 18th and early 19th century.-History:...

 folklorist Julius Krohn

Julius Krohn

Julius Leopold Fredrik Krohn was a Finnish folk poetry researcher, a professor of Finnish literature, a poet, a hymn writer, a translator and a journalist. He was born in Viipuri. Krohn worked as a lecturer on Finnish language in Helsinki University from the year 1875 and as a supernumerary ...

. According to legend, Krohn is said to have left for Central Europe after losing to his younger brother Leopold the competition for the hand of a Vyborg

Vyborg

Vyborg is a town in Leningrad Oblast, Russia, situated on the Karelian Isthmus near the head of the Bay of Vyborg, to the northwest of St. Petersburg and south from Russia's border with Finland, where the Saimaa Canal enters the Gulf of Finland...

 mansion owner's 15 year old daughter. He remained unmarried until his death at the age of 88.

Krohn worked at the University of Bonn

University of Bonn

The University of Bonn is a public research university located in Bonn, Germany. Founded in its present form in 1818, as the linear successor of earlier academic institutions, the University of Bonn is today one of the leading universities in Germany. The University of Bonn offers a large number...

 on zoology

Zoology

Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...

, anatomy

Anatomy

Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

 and embryology

Embryology

Embryology is a science which is about the development of an embryo from the fertilization of the ovum to the fetus stage...

. He was a pioneer in marine biology

Marine biology

Marine biology is the scientific study of organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather...

 and published essential works on Chaetognatha

Chaetognatha

Chaetognatha, meaning hair-jaws, and commonly known as arrow worms, are a phylum of predatory marine worms that are a major component of plankton worldwide. About 20% of the known species are benthic, that is belonging to the lowest zone of the ocean, or benthic zone, and can attach to algae and...

(Arrow Worms) in 1844 & 1853. He was in correspondence

Correspondence of Charles Darwin

The British naturalist Charles Darwin had correspondence with numerous other luminaries of his age and members of his family. These have provided many insights about the nineteenth century, from scientific exploration and travel to religious debate and discussion...

 with Charles Darwin

Charles Darwin

Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 and is said to have pointed out errors in Darwin's work in his thesis.
The genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 and species identified by him are marked with the author abbreviation Krohn. He was the first to classify the phylum

Phylum

In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....

 Rhombozoa

Rhombozoa

Dicyemida, or Rhombozoa, is a phylum of tiny parasites that live in the renal appendages of cephalopods. Although the name "Dicyemida" precedes "Rhombozoa" in usage, and is preferred by most contemporary authors, "Rhombozoa" still enjoys much popular support.Classification is controversial...

of the kingdom

Kingdom (biology)

In biology, kingdom is a taxonomic rank, which is either the highest rank or in the more recent three-domain system, the rank below domain. Kingdoms are divided into smaller groups called phyla or divisions in botany...

 Animalia.

The species Euphausia krohnii and Cliopsis krohnii

Cliopsis krohnii

Cliopsis krohnii Troschel, 1854. is the only species in Cliopsis, a genus of sea angels belonging to the family Cliopsidae.The Marine Species Identification Portal recognizes three morphs :...

and the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Eukrohniidae

Eukrohniidae

Eukrohniidae is a family of arrow worms.-History:The species Eukrohnia hamata was identified by Mobius in 1875.The genus was named Eukrohnia by Ritter-Zahony in 1909 after August David Krohn....

are named after him.