Sydney John Hickson was born in 1859 to a successful family of shoe and boot makers in London. Hickson attended the Mansion Grammar School in Leatherhead until 1876 before moving to University College School where he was taught by Ray Lankester, a leading zoologist. In 1877 he began his undergraduate degree at Downing College, Cambridge where in 1881 he received first class honours in Natural Sciences. After finishing university he became a demonstrator and laboratory assistant at Oxford. He specialised in insect eyes at this time and published an important paper on the Eye and Optic Tract of Insects in 1885.
By the mid-1880s Hickson's interests had shifted to marine biology and undertook an expedition to Makassar in the Celebes [Sulawesi], Dutch East Indies, to study soft corals. His researches progressed well until he was struck down with malaria. With no known cure Hickson was moved to north Makassar to recover. Whilst in High Makassar he studied the local population and its culture. Anthropological studies of this kind were still relevantly new and Hickson’s study was very important. On his return to England he published a book called A Naturalist in North Celebes (1889) which detailed both his survey of corals and the peoples of the High Makassar.
Hickson continued to travel after Celebes and made regular visits to Holland where he was held in high regard by the zoological community. In 1922 he was made a member of the Netherlands Zoological Society. In 1889 he toured Canada, America and Mexico for a year. On his return he became an advanced zoology lecturer in Cambridge.
As a zoologist, Hickson applied Darwinian evolutionism to the fields of morphology and embryology, and took a keen interest in the fledging area of genetics. His study of the sedentary coelenterates concluded that species can only be determined by method of experimental morphology, which was revolutionary at the time.
In 1894 Hickson was appointed Beyer Professor of Zoology at Owens College, succeeding Arthur Milnes Marshall. Whilst at Manchester he actively promoted research work, particularly for entomology, protozoology and vertebrate zoology. During his time at Manchester, Hickson published two more popular books, The Story of Life Under the Sea and The Fauna of the Deep Sea. He established the "Pleasant Friday Afternoons" meetings, with Professor F E Weiss [botany], where staff and students discuss the latest publications in biology and showed specimens. Hickson was also influential in changing the attitude towards women at the university. He refused to teach male and female students separately and was also instrumental in setting up many of the women’s athletic societies.
In 1895 he was elected Fellowship of the Royal Society, mainly for his work on Alcyonaria corals, on which he was the chief authority.
In 1896, he married Anne Maud Fletcher and they had a son and a daughter. He retired from Manchester University in 1926 but still continued to undertake research work at Cambridge. Hickson died on the 6th February 1940.