Guide to raising sunflower starfish ‘nearly finished’

By Scott Doggett
Posted 5/22/24



A top researcher for the University of Washington said that he expects to publish a book in coming months detailing how to raise sunflower sea stars that will hopefully show …

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Guide to raising sunflower starfish ‘nearly finished’




A top researcher for the University of Washington said that he expects to publish a book in coming months detailing how to raise sunflower sea stars that will hopefully show some resilience to the wasting disease that has killed nearly 6 billion of them in recent years.

The book could prove to be a crucial step to the species' recovery from the brink of extinction. It could also possibly serve as a tool to help in our understanding of poorly studied sea-star life cycles in general, preparing biologists for future outbreaks of the disease.

 The disease, which may be caused by bacteria (the jury is still out on that), has wiped out 95% of the sunflower sea star population and has impacted some 20 other sea star species along the Pacific Coast from Alaska to Baja California since it first appeared in 2013.

 In turn, the sunflower sea star crash has led to a population explosion of one of their favorite prey—the purple sea urchin—which in turn has annihilated kelp beds and marine eelgrass along the West Coast upon which countless species from abalone to salmon to orcas depend.

   Dr. Jason Hodin, a senior scientist at Friday Harbor Laboratories, a world-renowned marine research facility on San Juan Island, told The Leader in an exclusive interview that "we're hoping to literally produce what we call a cookbook for how to raise a sea star."

 "I call it a cookbook, because I literally think of it that way," Hodin said, adding that he envisions it as an indispensable tool for reproductive scientists. "Like, it'll be sitting on their shelves, an actual book that they can pull out, and they can say, 'wait a minute, we're seeing something weird here. This juvenile sea star looks abnormal.' "

 The scientists could then turn a section in the book where there's a photo that identifies the abnormality and provides information on what it likely is and how to respond to it.

 Further, Hodin said, "it's like a cookbook in the sense that it says at this time of year this is the method that you use to make sea stars if you have these kinds of facilities and you're approaching in this way. You add this many larvae to this much volume of sea water and it will give you this many sea stars in the end. Things like that."

 The book will feature "basic, straightforward protocols that people can follow—sections as you would have in a cookbook where it's like, wait, 'we don't have garam masala, we'll use cumin instead. It'll work just fine.' I mean, we'll have tips like that as well." 

 Hodin and other UW researchers have spent the past five years trying to raise sunflower sea stars. In the interview, he disclosed that the team has gone from producing sea stars from larvae several years ago to just this past year seeing juveniles grow into adults and have children of their own.

 The reproduction occurred while being exposed to the same disease-laced seawater found in the Puget Sound and along the coast from Alaska to the tip of Baja. Hodin speculated that their success might have been in part akin to a selection process where those juveniles more resilient to the disease might be more likely to survive.

 He said that success has led his team to consider what else could be done to help the sea stars.

 "You're automatically thinking about breeding for certain features, such as breeding for resilience to climate change, breeding for resilience to the disease that knocked them out, breeding for potentially greater predatory interest in species like purple urchins," he said.

   "That's what the power of doing captive breeding has for you. It allows you to be able to select for these features of interest and potentially from the point of view of restoration, make generations that are particularly resilient in different kinds of contexts." 

 The sunflower sea star is a remarkable organism. Unlike most starfish, it is soft-bodied; it relies on fluid pressure to maintain its body form. That allows it to glide 100 yards an hour without the benefit of an ocean current. It can have two dozen arms, weigh nearly 15 pounds and be two feet wide.

 In a 2021 paper, Hodin likened the sunflower sea stars to wolves and sharks, describing them top-tier predators. Over the past 50 years, he wrote, scientists have come to realize just how important such predators are to thriving ecosystems.

 "In the mid 1960s, University of Washington zoology professor Bob Paine first identified predatory sea stars as the so-called 'keystone species' in certain seafloor habitats: remove the keystone and the stable structure of the ecosystem falls apart."

 That's similar to what has happened with the kelp and the eelgrass, thanks to the voracious purple sea urchins.

 "At latest count, kelp in that region has been reduced to a mere 5% to 10% of its former numbers," Hodin wrote. "Kelp forests are well named: they are truly the rain forests of the ocean, providing crucial habitat for countless species of algae, fish and invertebrates, buffering the coasts from storms and mitigating climate change. Current conditions are dire."

 But while the recovery of sunflower sea stars in the wild has been uneven at best, Hodin still sees hope.

"When we started this work 5 years ago, we really had no idea if captive breeding was even possible, and there was not a lot of work happening at that point at all. Since then, there has been an explosion of interest among disease biologists, ecologists, larval biologists, and the public at large about the plight of this species. Things are definitely looking up for these charismatic stars."