Born Loisette Matilda Rutt in Mill Bay, British Columbia, she was an only child, who spent her earliest years exploring the sea and seashore adjacent to her home.

[4] She married Brian Marsh and together in 1960 they moved to Norfolk Island and then to Fiji in 1963.

[6] She joined the Western Australian Museum first as a part-time graduate assistant (1970-1973), becoming assistant curator marine invertebrates (1974-1977) and finally curator of marine invertebrates (1977-1993).

[6] In addition to her published research, she left 16 volumes of field notes, covering field work from 1972-1982 in the Fremantle area, off the shores the Western Australian coastline, including the Abrolhos Islands, Guam, Indonesia, Europe, Torres Strait, North-West Cape, New Guinea, and other places.

[7] She was awarded an AM in 2021 for services to marine science and zoology,[6] and the Whitley Award in 2021 for the field guide she co-authored with Jane Fromont, Field Guide to the Shallow Water Seastars of Australia.