(b. Bergen, Norway, 30 August 1805; d. Christiania [Oslo], Norway, 22 October 1869)
Sars’s father, for whom he was named, was born in Bremen but later settled in Bergen, as sea captain and merchant. The ancestors of his mother, Divert Henriche Heilmann, came from Narva, Estonia.
Sars’s early enthusiasm for natural history was much encouraged by his teachers. He studied theology and received the candidate’s degree in 1828. From 1828 to 1854 he served as teacher, vicar, and later rector of seashore communities in western Norway, often traveling by boat to visit parishioners and devoting much of his time to zoological studies. Some of his most important work was done in this period. Following his appointment on 7 August 1854, Sars was professor extraordinarius of zoology at the University of Christiania (Oslo) until his death; but his excessive concern with details of morphology made him neither a successful nor a popular teacher.
His marriage in 1831 to Maren Welhaven produced twelve children, one of whom, Georg Ossian, became a noted zoologist.
Sars traveled widely in his younger years, beginning with a journey to the northern seas of Norway. A large grant supported a six-month natural history trip in 1837 to Holland, France, Germany, Prague, Denmark, and Sweden. Sars often visited the Mediterranean, the Adriatic in 1851, and Naples and Messina in the winter of 1852–1853. These study trips not only greatly increased his knowledge but also brought him in contact with the leading zoologists of Europe.
One of the fathers of marine zoology Sars from 1830 to 1860 made what is perhaps the greatest single contribution to the elucidation of the life cycles of marine invertebrates. His findings on the alternation of generations in coelenterates were among the most important evidence for Steenstrup’s classical work on Generationswechsel (1842). Because the larval stages of most marine organisms are so different from the adults, their connections cannot be discovered until a series of intermediate stages is established; it was Sars who discovered many of them. Simultaneously with the Swedish zoologist Sven Lovén he found and described the first trochophore larvae (annelid). Like-wise, Sars was the first to describe the veliger larvae of the mollusks (1837, 1840) and the bipinnaria larva (1835), which he later (1844, 1846) identified as a stage in the development of starfish.
From 1830 on, Sars used the dredge invented by O. F. Müller in his collecting. His numerous discoveries of deep-sea organisms by dredging were a sensation in his day because–until he proved otherwise–it had been universally assumed that the depths of the ocean where light did not penetrate were without life. In 1864 his son Georg, who participated in the collecting, dredged up from a depth of 300 fathoms (near Lofoten) the first living stalked crinoids (sea lilies), a group of organisms then known only from fossils and thought to have been extinct since the Mesozoic. The description of Rhizocrinus lofotensis (1864) was followed by intensified work at greater ocean depths, and in 1868 Sars published a memoir on 427 species of invertebrates collected off Norway at depths of from more than 200 to 450 fathoms. These exciting results induced him to promote deep-sea expeditions and thus led to the conception and organization of the Challenger expedition.
Although a competent taxonomist and morphologist, Sars was interested mainly in life cycles, larval stages, parental care through brood pouches, seasons of reproduction, cyclic phenomena, and migrations of marine organisms. His own research yielded major contributions to knowledge of annelids, ascidians, coelenterates, crustaceans, echinoderms, and mollusks. Actively interested in fossils, he also published a number of contributions to paleontology.
Sars published ninety-five papers (six posthumous). He was an honorary or corresponding member of more than twenty foreign academies and societies and was awarded honorary doctorates from the universities of Zurich (1846)and Berlin (1860). Most of his original publications appeared in Norwegian; but some were subsequently republished, at least in abstract, in French, English, or German.
I. original Works A complete bibligraphy of Sars’s works is found in Økland (below); they include Beskrivelser og iagttagelser over nogle... ved den Bergenske kyst levnde dyr (Bergen, 1835), French abstract in Annales d’anatomie et de physiologie, 2 (1838), 81–90; “Beitrag zur Entwicklungsgeschichte der Mollusken und Zoophyten”, in Archiv für Naturgeschichte, 3 (1837), 402–407; 6 (1840), 196–219; “Mémoire pour servir à la connaissance des crinoïdes vivants”, in University Program, first semester 1867 (Christiania, 1868); and “On Some Remarkable Forms of Animal Life From the Great Deeps of the Norwegian Coast I”, ibid., first semester 1869 (Christiania, 1872), written with G. O. Sars.
II. Secondary Literature Information on Sars’s life and work is in Fridthjof Økland, Michael Sars et Minneskrift (Oslo, 1955), which has a full bibliography; the obituary by Gwynn Jeffreys in Nature, 1 (1870), 265–266; and J. J. S. Steenstrup, Ueber den Generationswechsel (Copenhagen, 1842).