Patricia Marjorie Ralph was born in Wellington on 5 April 1920, the daughter of Clarence John Ralph, an electrical engineer, and his wife, Elin Elfie Jacobson. She attended Brooklyn School then Wellington Girls’ College, where she won several prizes in scripture knowledge and was made a prefect in her final year.
In 1938 Pat Ralph entered Victoria University College. She graduated BSc in 1941 and MSc (with a thesis on sea slugs) in 1943, when she also became a demonstrator in the biology department. In 1945 she was appointed a junior lecturer and in 1949 received a tenured position. By then the department had been split into the departments of zoology and botany; Ralph taught in zoology, continuing her specialisation in invertebrates.
In 1947 she conducted a party of science students to the United States and Canada. Focusing on visits to marine laboratories, they saw apparatus not yet used in New Zealand, such as the electron microscope and the cyclotron. With a Nuffield travelling scholarship Ralph visited England in 1958–59, continuing with her work in marine biology. She was made a senior lecturer in zoology in 1959 and a reader in 1967, becoming the first woman to hold such a position in the science faculty at Victoria.
Ralph specialised in marine hydroids, which before she began publishing were little studied in New Zealand; she published five seminal papers on the thecate hydroids of New Zealand between 1957 and 1961. Her pioneering work won worldwide recognition and in 1962 she received the rarely given DSc; she was the first woman on the staff of Victoria to receive the degree. The following year she and J. A. F. Garrick of the zoology department attended the International Congress of Zoology in Washington, representing Victoria University. She then visited various laboratories in order to compare their cubomedusan jellyfish collections.
Pat Ralph was an exceptionally gifted teacher: energetic, innovative and warmly encouraging to students, with whom she was very popular; some went on to publish in marine biology. She was particularly interested in the welfare of women students. She had a strong practical streak, and was skilful in the use of teaching aids, making slides for students and writing booklets to help them with their laboratory work. Ralph frequently went out into Wellington Harbour and Cook Strait in the university boat in search of suitable specimens. She was involved in the formation of the Victoria University College Biology Society and in its journal, Tuatara. When the new Kirk Building was planned, she was actively involved in the planning of the laboratories and in the design of the windows, and recorded the construction of the building on film.
In 1971 Ralph took early retirement after her mother became ill. She was invited to return to work when her mother died not long afterwards, but declined. Instead she tried to establish a business providing scientific slides and specimens to schools, but the venture proved difficult to sustain.
Ralph was an active member of the Wellington branch of the New Zealand Federation of University Women and for years convened its academic dress committee. She was brought up in the Methodist church and retained her religious faith throughout her life. When there was a shortage of ministers in her area she undertook to visit the sick and dying. She never married and in the early 1980s moved to Paraparaumu, where she died on 23 March 1995.
In honour of Pat Ralph’s outstanding contribution to marine biology two new species of coral were named after her: Sphenotrochus ralphae and Caryophyllia ralphae. Her work was all the more remarkable in that it was done at a time when New Zealand scientists worked in relative isolation from the rest of the scientific community. A quiet, modest woman, she was highly regarded overseas, and in New Zealand was valued by her colleagues and students for her integrity and helpfulness.