Marusik was born in Sarny, a small town in West Ukraine, to Mikhail Adamovich, a school teacher, and Tamara Andreevna, a nurse.
Marusik started his studies at Leningrad (now Saint Petersburg) State University in 1979 where he specialized in entomology under the supervision of Victor P. Tyshchenko.
After his graduation in 1984, Marusik was accepted into a Ph.D. program in Magadan, working in the lab of Daniil I. Berman.
His Ph.D. dissertation (1988) was devoted to fauna, population structure and spatial distribution of spiders in the upper reaches of the Kolyma River, northeastern Siberia.
[1][2] Marusik has published over 500 scientific papers dealing with taxonomy, systematics, faunistics and the biogeography of spiders and other invertebrates.