Eugenie Clark was born and raised in New York City. Her father, Charles Clark, died when she was a small child, and she was raised by her mother, Yumico, who was of Japanese descent. She became fascinated by fish through visits to the New York Aquarium and kept collections of fish, amphibians, and reptiles in her apartment.
She received a bachelor's degree in zoology from Hunter College, and master's and doctoral degrees from New York University. Shortly after graduating from college, she married Jideo Umaki, a pilot; their marriage ended in divorce. As part of her graduate studies, she did research at the Scripps Institute of Oceanography in La Jolla, California; at the American Museum of Natural History in New York; at the Marine Biological Laboratory in Woods Hole, Massachusetts; and at the Lerner Marine Laboratory in Bimini. Her research and travels in Micronesia formed the subject of her first book, Lady with a Spear (1953), which became a bestseller. In 1950, she won a Fulbright Scholarship for ichthyological studies at the Marine Biological Station in Hurghada, on the northern Red Sea coast of Egypt. There she married her second husband, Ilias Papakonstantinou, a Greek physician, with whom she had four children. Clark became renowned as a pioneer in marine conservation and helped the public understand and appreciate sharks. She wrote articles for scientific journals and popular magazines such as National Geographic and Science Digest. Her other books included The Lady and the Sharks (1969) and The Desert Beneath the Sea (1991), a children's book written with Ann McGovern.