Peter Ax (March 29, 1927 – May 2, 2013) was a German zoologist. His main work concerned the investigation of interstitial fauna and the exposition of a phylogenetic system for the

animals Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a ...

Biography

Peter Ax attended the Oberschule für Jungen in

Hamburg Hamburg (, ; ), officially the Free and Hanseatic City of Hamburg,. is the List of cities in Germany by population, second-largest city in Germany after Berlin and List of cities in the European Union by population within city limits, 7th-lar ...

until 1944 and subsequently completed his military service. He studied biology at the

University of Kiel Kiel University, officially the Christian Albrecht University of Kiel, (, abbreviated CAU, known informally as Christiana Albertina) is a public research university in the city of Kiel, Germany. It was founded in 1665 as the ''Academia Holsator ...

from 1946, and graduated with a doctorate in 1950. From 1952 to 1961, he was employed as a scientific worker at the same university. He gained his

habilitation Habilitation is the highest university degree, or the procedure by which it is achieved, in Germany, France, Italy, Poland and some other European and non-English-speaking countries. The candidate fulfills a university's set criteria of excelle ...

in 1955, and worked as a

Dozent The term "docent" is derived from the Latin word , which is the third-person plural present active indicative of ('to teach, to lecture'). Becoming a docent is often referred to as habilitation or doctor of science and is an academic qualifica ...

. In 1961, he went to the University of

Göttingen Göttingen (, ; ; ) is a college town, university city in Lower Saxony, central Germany, the Capital (political), capital of Göttingen (district), the eponymous district. The River Leine runs through it. According to the 2022 German census, t ...

, where he held the chair in Morphology and Systematic Zoology. He remained there until his retirement as an

emeritus professor ''Emeritus/Emerita'' () is an honorary title granted to someone who retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". In some c ...

in 1992.

Research

Peter Ax worked primarily on the

micro- ''Micro'' (Greek letter μ, Mu (letter), mu, non-Italic type, italic) is a metric prefix, unit prefix in the metric system denoting a factor of one millionth (10−6). It comes from the Ancient Greek, Greek word (), meaning "small". It is the ...

and

meiofauna Meiobenthos, also called meiofauna, are small benthic invertebrates that live in marine or freshwater environments, or both. The term ''meiofauna'' loosely defines a group of organisms by their sizelarger than microfauna but smaller than macrof ...

of the interstitial environment in marine sediments, and on the systematics of

flatworms Platyhelminthes (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called ...

. He described an array of hitherto unknown species from this environment, including ''Diplosoma micans'', the first

tunicate Tunicates are marine invertebrates belonging to the subphylum Tunicata ( ). This grouping is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ...

to be found in the interstitial habitat, in 1970. In 1956 he was the first to describe the

Gnathostomulida Gnathostomulids, or jaw worms, are a small phylum of nearly microscopic marine animals. They inhabit sand and mud beneath shallow coastal waters and can survive in relatively anoxic environments. They were first recognised and described in 1956. ...

, which was also found from this habitat. Through his works such as ''Das phylogenetische System'' (1984) and the three-volume ''Das System der Metazoa'' (1995-2001), he also became known as one of the important exponents of

phylogenetic systematics Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

in Germany.

Memberships and awards

Peter Ax was the founding editor of the journal ''Mikrofauna marina''. He worked as a guest scientist at the

Friday Harbor Laboratories Friday Harbor Laboratories (FHL), is a marine biology field station of the University of Washington, located in Friday Harbor, San Juan Island, Washington, United States. Friday Harbor Labs is known for its intensive summer classes offered to co ...

of the

University of Washington The University of Washington (UW and informally U-Dub or U Dub) is a public research university in Seattle, Washington, United States. Founded in 1861, the University of Washington is one of the oldest universities on the West Coast of the Uni ...

, at the marine biological stations in

Arcachon Arcachon (; ) is a commune in the southwestern French department of Gironde. It is a popular seaside resort on the Atlantic coast southwest of Bordeaux, in the Landes forest. It has a sandy beach and a mild climate said to be favourable for p ...

Banyuls-sur-Mer Banyuls-sur-Mer (; ) is a Communes of France, commune in the Pyrénées-Orientales Departments of France, department in southern France. Geography Location Banyuls-sur-Mer is located in the canton of La Côte Vermeille and in the arrondissemen ...

, and

Naples Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...

, and at the Darwin Station on the Galapagos Islands. He was a member of the

Akademie der Wissenschaften und der Literatur The Academy of Sciences and Literature () is a scientific academy in Mainz, Germany. It was established in 1949 on an initiative of Alfred Döblin. The academy's goal is to support science and literature, and in doing so to help preserve and pr ...

Mainz Mainz (; #Names and etymology, see below) is the capital and largest city of the German state of Rhineland-Palatinate, and with around 223,000 inhabitants, it is List of cities in Germany by population, Germany's 35th-largest city. It lies in ...

, a fellow at the

Institute for Advanced Study, Berlin The Institute for Advanced Study in Berlin () is an interdisciplinary institute founded in 1981 in Grunewald (locality), Grunewald, Berlin, Germany, dedicated to research projects in the natural and social sciences. It is modeled after the orig ...

in 1986/87, and an honorary member of the Gesellschaft für Biologische Systematik.

Selected works available in English

* ''The phylogenetic system: The systematization of organisms on the basis of their phylogenies''. (Original: ''das phylogenetische System'') Chicester: Wiley, 1987. * ''Multicellular animals: The phylogenetic system of the Metazoa'' (Original: ''Das System der Metazoa'') Berlin: Springer, 1996-2003. (3 vols.) ** ** p. 364
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References

* {{DEFAULTSORT:Ax, Peter German evolutionary biologists 2013 deaths 1927 births 20th-century German zoologists Members of the Göttingen Academy of Sciences and Humanities