Walking Sharks and the Great Zebra vs. Leopard Shark Debate with Dr. Chris Dudgeon

Dr. Chris Dudgeon has spent more than two decades studying some of the ocean's strangest and least understood sharks, from the reef-walking Hemiscyllium species of Papua New Guinea and Indonesia to the shape-shifting zebra shark that spends its youth striped and its adulthood spotted. In this episode, hosts Andrew Lewin and Dr. David Ebert sit down with Chris, a senior researcher who bridges evolutionary biology, population genetics, and applied conservation, to unpack why a single species can carry two completely different common names, how a newly discovered walking shark came to be named after her, and what it actually took to build a rewilding program from scratch.

The conversation traces Chris's path from a landlocked childhood in Canberra to the front lines of Australian shark science, including her role as a founding member of the Oceania Chondrichthyan Society and her work describing new walking shark species alongside taxonomist Gerry Allen. She walks through the surprising biogeography of Papua New Guinea's walking sharks, where distinct species turn up within a short distance of each other with no obvious barrier explaining the split, and the practical realities of doing fieldwork where saltwater crocodiles share the water. The back half of the episode is devoted to the StAR Project, the rewilding effort that raises zebra shark pups from eggs supplied by aquariums around the world and releases them into the wild in Indonesia and Thailand, and to the taxonomic history behind why scientists now call the species Stegostoma tigrinum rather than Stegostoma fasciatum.

Along the way, Chris shares a personal tribute to her late PhD supervisor, Janet Lanyon, reflects on what it means to build a research career with no roadmap to follow, and offers direct advice for the next generation of aspiring marine scientists. It is a wide-ranging look at how careful taxonomy, genetics, and community partnerships come together to protect species most people have never heard of, let alone seen.

Takeaways

• Zebra sharks and leopard sharks are common names for the same Indo-Pacific species, Stegostoma tigrinum, which is striped as a juvenile and spotted as an adult; the confusion exists because a completely unrelated species, Triakis semifasciata, is also called a leopard shark in the eastern Pacific.
• A 2018 taxonomic review found that the species' correct scientific name should be Stegostoma tigrinum, not Stegostoma fasciatum, because an earlier valid name had been overlooked.
• Walking sharks (genus Hemiscyllium) use their pectoral and pelvic fins to "walk" across reef flats, mostly at night, and new species are still being described in Papua New Guinea and eastern Indonesia.
• A newly described walking shark species was named after Chris by her own PhD student, Jess Blakeway.
• The StAR Project (Stegostoma tigrinum Augmentation and Recovery) rewilds zebra sharks bred from aquarium-supplied eggs, with active hatchery and release programs in Raja Ampat, Indonesia and the Gulf of Thailand.
• Chris was a founding member of the Oceania Chondrichthyan Society in the mid-2000s, part of a small cohort of students who built the region's shark research community largely from scratch.
• Chris's advice for aspiring marine scientists: pick an understudied species to build genuine expertise faster, expect the path to feel anything but linear, and be prepared to figure things out without a roadmap.

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