Successful Spawning and Cross-Fertilization Bring Hope for the Critically Endangered Sunflower Star

SAN FRANCISCO, CA (February 26, 2024) – Love is in the water and hope is in the air for the critically endangered Sunflower star (Pycnopodia helianthoides) as a multi-institution collaborative team from the California Academy of Sciences, Aquarium of the Pacific, Birch Aquarium, San Diego Zoo Wildlife Alliance, and Sunflower Star Laboratory successfully spawned and cross-fertilized sperm and eggs from a male and a female, resulting in fertile embryos that will be raised to bolster populations in human care. This success marks another step forward in an ongoing collaborative effort between organizations across the state to save the species from extinction.

The resulting embryos from the spawning event—which took place on Valentine’s Day at Birch Aquarium at Scripps Institution of Oceanography at UC San Diego—were transported to the Academy’s Steinhart Aquarium where biologists will employ their larval rearing expertise to raise the young sea stars to adulthood. The goal is to learn the best rearing practices for this particular species so that future generations of lab-spawned Sunflower stars can be outplanted back to their native kelp forests along the California coast.

“In order for future outplanting efforts to be successful, we need to develop protocols for rearing them in high numbers in an aquarium setting,” says Steinhart Aquarium Curator Kylie Lev. “While this is the first time Steinhart Aquarium has housed Sunflower star larvae, we’ve raised a number of animals through our larval rearing program, from corals to bat stars to sea urchins. By replicating the aquaculture techniques we’ve developed and adjusting them to fit the specific needs of Sunflower stars, we can increase their population numbers and bolster their genetic diversity.”

The embryos rapidly developed into free-swimming larvae within their first two days of life and will settle into the familiar five-legged star shape in about three months. Until then, they need to be kept in moving water. To support such a large quantity of larvae, the Steinhart team piloted novel rearing techniques using more common sea star species, namely bat stars and ochre stars. They found that the most effective tool to raise large quantities of larvae in the smallest amount of space is a budget-friendly kitchen appliance: an automated pot-stirrer.

Unlike other species within Steinhart’s larval rearing program, Sunflower stars are cannibalistic, meaning they could decimate their own population before they reach adulthood. After their three-month pot-stirrer swirl, the baby sea stars will be moved to an underwater nursery specially designed to isolate individuals. The team will also introduce foods with varying nutritional profiles to determine a diet plan that keeps the baby sea stars happy and healthy—without resorting to cannibalism.

While the spawning and subsequent larval rearing were made possible by the ongoing collaboration across five California institutions, it also marks a partnership within the Academy between the Steinhart animal husbandry team and the Institute for Biodiversity Science and Sustainability (IBSS), the Academy’s research arm. Academy researchers will genetically sequence sea stars at both larval and settlement stages to identify genetic markers that may contribute to the species’ survival.

For Center for Biodiversity and Community Science Co-Director Alison Young, this collaboration is a vital step in regenerating coastal California ecosystems:

“Sunflower stars play a critical role in balancing coastal kelp forest ecosystems, but sea star wasting disease has slashed their population numbers by more than 90% in just a decade. These predatory sea stars help keep sea urchin populations in check, so without Sunflower stars, these voracious marine herbivores are decimating California’s kelp forests. By leveraging our in-house expertise and partnering with other aquariums to hone techniques to successfully raise Sunflower stars in human care, we can bring back this iconic, threatened species and preserve the opportunity to see this magnificent animal in our waters again. Mobilizing our collective expertise to take action for nature in our home state is a cornerstone of the Academy’s Thriving California initiative.”

This collaboration is part of the Association of Zoos and Aquariums (AZA) SAFE Sunflower Sea Star Program, co-led by the Aquarium of the Pacific and Omaha’s Henry Doorly Zoo & Aquarium. It also contributes to a comprehensive multi-faceted, multi-partner “Roadmap to Recovery,” led by The Nature Conservancy, to help accelerate the recovery of this species along the West Coast.

Assets:

• Photos and b-roll

Media Contacts:

• Steinhart Aquarium at California Academy of Sciences | Megan Ely, mely@calacademy.org
• Aquarium of the Pacific | Marilyn Padilla, mpadilla@lbaop.org, 562-951-1684 \ Andreas Miguel, amiguel@lbaop.org, 562-951-1678
• Birch Aquarium at Scripps | Alex Feltes, afeltes@ucsd.edu \ Joanna Volavka, jcvolavka@ucsd.edu
• San Diego Zoo Wildlife Alliance | Andrew James, ajames@sdzwa.org
• Sunflower Star Laboratory | Ashley Kidd, ashley@sunflowerstarlab.org