For the first time, scientists have received help from sea lions in mapping the seafloor. And the marine mammals have done their job well: They have mapped six different marine habitats, including algal meadows and reefs that make up the seafloor of southern Australia, researchers report in a recently published study.

For much of our planet’s oceans, the seafloor looks like this: still a mysteryConventional surveys using special underwater equipment and vessels require large crews and good weather, making mapping large areas difficult and expensive, Nathan Angelakis, lead author of the study and a doctoral student at the University of Adelaide in Australia, told Mongabay in an email.

As an alternative, the researchers equipped eight adult female Australian sea lions (Neophoca cinerea). The team had two goals: to understand the habitats and food critical to the endangered species and to map the little-known seafloor off the coast of South Australia.

The sea lion videographers ended up recording more than 89 hours of data and footage, covering around 560 kilometers of the continental shelf at depths ranging from 5 to 110 meters. When analyzing this data, the scientists found that the sea lions eat a variety of fish, small sharks, stingrays and squid by either turning over rocks, digging up sand or ambushing schools of fish. “We were also lucky enough to capture footage of a mother taking her pup on a trip out to sea. This is the first direct evidence that Australian sea lion mothers pass on their foraging skills to their pups,” Angelakis said.

The team also identified six types of seafloor habitat from the videos. They combined this habitat data at different locations with long-term oceanographic and ecological data for those locations to then predict habitats for areas that the sea lions did not visit. “This allowed us to map and predict seafloor habitats for more than 5,000 square kilometers of previously unexplored seafloor along the continental shelf of southern Australia,” Angelakis said.


Sea lion swims through an invertebrate reef, a sponge garden, a macroalgae reef, bare sand, and invertebrate boulder habitats. Video: Angelakis et al. 2024.

Katie Dunkley, a marine scientist at the University of Cambridge in the UK who was not involved in the study, said: The Washington Post that although the number of sea lions used in the study was small, the study was a proof of concept that showed that sea lions can help us map the seafloor.

Angelakis added that such fundamental knowledge of seafloor habitats and the conditions that affect their distribution is crucial “to understand how they can be affected by human activities.” In addition, the study improves our understanding of the marine habitats that are crucial for the rapidly decreasing Australian sea lions, he said.

“This information is essential to better protect and manage their populations in the future,” Angelakis added.

Banner image of the Australian sea lion by John Turnbull via Flickr (CC BY-NC-SA 2.0).