Karl Ritter von Frisch (20 November 1886 – 12 June 1982) was a German-Austrian ethologist who received the Nobel Prize in Physiology or Medicine in 1973, along with Nikolaas Tinbergen and Konrad Lorenz.
His work centered on investigations of the sensory perceptions of the honey bee and he was one of the first to translate the meaning of the waggle dance. His theory, described in his 1927 book Aus dem Leben der Bienen/ (English: "From the Life of Bees", published in the UK and United States as The Dancing Bees), was disputed by other scientists and met with widespread skepticism at the time, only decades later being appreciated as both zoologically accurate and an important step in development of animal behavioral study, and the wider history of biology.
Karl Ritter von Frisch was the son of the surgeon and urologist Anton von Frisch, by his marriage to Marie Exner. Karl was the youngest of four sons, all of whom became university professors. Von Frisch was of partial Jewish heritage.
Karl studied at the University of Vienna under Hans Leo Przibram and in Munich under Richard von Hertwig, initially in the field of medicine, but later turned to the natural sciences. He received his doctorate in 1910 and in the same year started work as an assistant in the zoology department of the Ludwig-Maximilians-Universität München.
In 1912, he became a lecturer in zoology and comparative anatomy there; and in 1919 was promoted to a professorship. His research on honeybees was continued by his student Ingeborg Beling. In 1921 he went to Rostock University as a professor of zoology and director of an institute. In 1923 he accepted the offer of a chair at Breslau University, returning in 1925 to the Ludwig-Maximilians-Universität München, where he became the head of the institute of zoology.
Von Frisch attracted negative attention from the Nazi regime, among other things for employing Jewish assistants, including many women. Eventually Frisch was forced into retirement, but the decision was reversed because of his research on nosema infections in bees. In the original edition of his book "Du und das Leben" ("You and Life") he wrote in support of the Nazi Law for the Prevention of Hereditarily Diseased Offspring
The institute of zoology was destroyed in the Second World War, and in 1946, Frisch went to work at the University of Graz, remaining there until 1950, when he returned to the reopened Munich institute. He retired in 1958 but continued his research.
Karl Ritter von Frisch married Margarete, née Mohr, who died in 1964. Their son, Otto Ritter von Frisch, was director of the State Natural History Museum in Braunschweig, Germany between 1977 and 1995.
Frisch studied aspects of animal behaviour, including animal navigation, in the Carniolan honey bee (Apis mellifera carnica), a subspecies of the European honey bee.
Frisch discovered that bees can distinguish various blossoming plants by their scent, and that each bee is "flower constant". Surprisingly, their sensitivity to a "sweet" taste is only slightly stronger than in humans. He thought possible that a bee's spatial sense of smell arose from the firm coupling of its olfactory sense with its tactile sense.
Frisch was the second to demonstrate that honey bees had color vision (first was Charles Henry Turner), which he accomplished by using classical conditioning. He trained bees to feed on a dish of sugar water set on a colored card. He then set the colored card in the middle of a set of gray-toned cards. If the bees see the colored card as a shade of gray, then they will confuse the blue card with at least one of the gray-toned cards; bees arriving to feed will visit more than one card in the array. On the other hand, if they have color vision, then the bees visit only the blue card, as it is visually distinct from the other cards. A bee's color perception is comparable to that of humans, but with a shift away from the red toward the ultraviolet part of the spectrum. For that reason bees cannot distinguish red from black (colorless), but they can distinguish the colors white, yellow, blue and violet. Color pigments which reflect UV radiation expand the spectrum of colors which can be differentiated. For example, several blossoms which may appear to humans to be of the same yellow color will appear to bees as having different colors (multicolored patterns) because of their different proportions of ultraviolet.
Frisch's experiments caused a reaction from established professor Carl von Hess, who had concluded in his 1912 book Vergleichende Physiologie des Gesichtssinnes (Comparative Physiology of Vision) that invertebrates and fish were colour-blind. He published an experimental paper in 1913 (before Frisch could publish) and disputed Frisch's knowledge, professionalism and conclusions, and those of John Lubbock before him. Frisch highlighted the errors in Hess's experimental method and asked him to desist.
Frisch's investigation of a bee's powers of orientation were significant. He discovered that bees can recognize the desired compass direction in three different ways: by the Sun, by the polarization pattern of the blue sky, and by the Earth's magnetic field, whereby the Sun is used as the main compass, with the alternatives reserved for the conditions arising under cloudy skies or within a dark beehive.
Light scattered in a blue sky forms a characteristic pattern of partially polarized light which is dependent on the position of the Sun and invisible to human eyes. With a UV receptor in each of the lens units of a compound eye, and a UV filter oriented differently in each of these units, a bee is able to detect this polarization pattern. A small piece of blue sky is enough for a bee to recognize the pattern changes occurring over the course of a day. This provides not only directional but also temporal information.
Frisch proved that variations in the position of the Sun over the course of a day provided bees with an orientation tool. They use this capability to obtain information about the progression of the day deep inside a dark beehive comparable to what is known from the position of the Sun. This makes it possible for the bees to convey always up-to-date directional information during their waggle dance, without having to make a comparison with the Sun during long dance phases. This provides them not only with alternative directional information, but also with additional temporal information.
Bees have an internal clock with three different synchronization or timekeeping mechanisms. If a bee knows the direction to a feeding place found during a morning excursion, it can also find the same location, as well as the precise time at which this source provides food, in the afternoon, based on the position of the sun.
Based on the magnetic field, the alignment of the plane of a honeycomb under construction (e.g., the new honeycomb of a swarm) will be the same as that of the home hive of the swarm, according to Frisch. By experiment, even deformed combs bent into a circle can be produced.
The vertical alignment of the honeycomb is attributed by Frisch to the ability of bees to identify what is vertical with the help of their head used as a pendulum together with a ring of sensory cells in the neck.