A marine animal is an organism that partially or entirely inhabits marine environments, encompassing a vast diversity of life forms ranging from microscopic plankton to massive whales. Authors such as Mrs. Loudon emphasized their ecological roles, pointing out how species like Arctic seals depend on oceanic prey, while Louis Figuier examined their interactions with human activity, such as following vessels for sustenance. William S.
Furneaux described their varied diets, from filter-feeding to hunting, and Julien Thoulet underscored their importance to human economies and cultures. Richard Lydekker categorized coastal fauna, highlighting their ecological value, and Charles Darwin observed their ability to adapt to environmental shifts. These viewpoints collectively illustrate marine animals as biologically diverse and deeply connected to human history and natural systems.