In December 2020, the International Union for Conservation of Nature updated the sunflower sea star’s status to critically endangered, but we have reason to believe that there may be remnant populations in the cold, deep fjords of British Columbia.
What is a sunflower star?
As a diver, you’ve likely witnessed hundreds– if not thousands– of sea stars. But none can compare to the sunflower sea star. If you’ve encountered this creature underwater, it’s an unforgettable experience. Perhaps you recall the sea star’s beauty, with vibrant coloring in any arrangement of purple, brown, green, pink, orange, or yellow. Or maybe you remember its size? The sunflower star is one of the largest sea stars in the ocean, growing up to one meter in diameter.
Juvenile sunflower stars begin life with just five arms, but adults can have up to 24 limbs with a total of 15,000 tube feet. And those tubes are made for walking! The radially symmetrical sunflower star is one of the fastest sea stars in the world– moving up to one meter per minute to capture its prey. Those tube feet lend to its scientific name, Pycnopodia helianthoides. Pycnopodia means many or dense footed, while helianthoides refers to the sea star’s sunflower-like appearance.
These predatory sea stars have a varied diet. On the menu are crabs, sea cucumbers, snails, chitons, sand dollars, dead or dying squid, other sea stars, and their favorite– sea urchins, which compose 21-98% of its diet. The sunflower star’s flexible body is composed of loosely connected aboral skeletal plates, which allows it to devour an entire sea urchin in one piece before expelling the urchin’s external shell. Natural predators of the sunflower star are large fish and the king crab, which the sunflower stars attempt to escape by shedding arms caught in the predator’s grasp and regenerating them once they’re in a safe location.
The sunflower star lives in the low intertidal zone on rocky shores and has been spotted at depths of up to 437 meters.
Where can divers find sunflower stars?
While you’ll certainly recall experiences with the sunflower star, it’s likely you haven’t seen one recently. Once a common sight in the northeast Pacific from Mexico to Alaska, sunflower stars are becoming rarer with each passing year. In 2013, an underwater epidemic decimated 80-100% of the sea star population across a 3,000 kilometer stretch of ocean. More than 5.75 billion of these resilient sea stars were turned into puddles of gelatinous goop once infected by sea star wasting syndrome. In SciTech Daily, Oregon Tech University reported that “No stars have been seen in Mexico since 2016, none in California since 2018, and only a handful in Oregon and Washington since 2018.”
In early summer 2019, The Hakai Institute began seeing signs of recovery with the reemergence of juvenile sea stars in June and July. By August and September, though, it was clear that the juveniles did not survive another wave of the wasting syndrome.
What is sea star wasting syndrome?
The sunflower star isn’t alone in facing the devastation of sea star wasting syndrome. At least 20 other species also experienced a massive decline after infection from 2013 to 2014. This isn’t a long-lasting illness. A series of three photos from Guemes Island, Washington show a relatively healthy-looking sea star transform into a puddle of goop in just three days. The disease begins when the sea star is afflicted by lesions and progresses as the tissue around the lesions begins to decay, eventually leading to the disintegration of the sea star.
One study at Cornell University showed a link between sea star associated densovirus (SSaDV) and affected sunflower stars, however, other sea stars affected by sea star wasting syndrome were not affected by SSaDV. Cornell University is working on a project to conduct molecular sequencing to discover the root cause of the syndrome that’s affecting so many sea stars.
At this time, sea star wasting syndrome is believed to be caused by a viral infection, but researchers are still unclear on its exact cause or how it spreads. While scientists continue to research the disease, there is one link that continues to show up in their studies.
If you guessed climate change, you’re right. Scientific divers noticed a correlation between sea star decimation and abnormally high water temperatures. The Blob, which formed in 2014, refers to an area of unusually warm water on the West Coast of the US and Canada that’s over 1,600km wide and almost 100 meters deep. The reemergence of the underwater heatwave two years ago is called the Northeast Pacific Marine Heatwave of 2019.
While it hasn’t yet been proven, many believe that the heightened temperatures in the Blob exacerbate the effects of sea star wasting syndrome. Oceanographers and climatologists continue to study this phenomenon and the effects it’s having on marine wildlife.
What are the marine biology implications if sunflower stars disappear forever?
Sunflower stars are most commonly found in kelp forests and play an important role in maintaining the health of the underwater ecosystem. Without sunflower stars to keep the sea urchin population in check, urchins are decimating the kelp forests. In addition to providing a home for marine creatures, kelp forests oxygenate the ocean, protect the coast from erosion, and play a vital role in repressing climate change.
A lack of sunflower stars to eat the urchins combined with underwater heatwaves put the kelp forests (and all who inhabit them) in danger.
What’s being done to protect sunflower sea stars?
Until we know more about the cause of the sea star wasting syndrome, it’s nearly impossible to mitigate its effects. In the meantime, the University of Washington and The Nature Conservancy have partnered on a program to breed sunflower stars in captivity. In early 2021, thousands of juvenile sea stars metamorphosed from larvae into mini sunflower stars at Friday Harbor Laboratories on San Juan Island in Washington. This program is intended to guard against extinction and be a source for recovery; scientists hope to one day release these sunflower stars into the ocean when it is deemed safe by scientists and wildlife agencies. For now, the scientists are learning as much as possible about the sunflower star’s biology and life cycle.
The largest marine wildlife disease on record has shrunk the global population of sunflower sea stars by 90%. Without change, their critically endangered status could transition to extinct. The loss or reemergence of sunflower stars has a ripple effect on their communities (and ours), and their status should not be taken lightly.
SCUBA divers, scientific divers, and commercial divers, we're in the best position to witness the shifts in the ocean...
Studies show that cooler temperatures may be the key to finding surviving sunflower stars, and we need your help. Up to 90% of these marine creatures have been destroyed, but 10% are still out there. Can you help us find them?
Scientists and recreational divers have conducted over 61,000 surveys to supply IUCN with the data needed to list sunflower sea stars as a critically endangered species, but we need boots on the ground (or fins in the water) to continue searching. Until this point, the long-term underwater research has enabled researchers to discover where sunflower star populations are the hardest hit, and conditions that allow the sea stars to survive.
Since sunflower stars in cooler waters are less affected by sea star wasting disease than their relatives in abnormally warm water, we believe there may be remnant populations of sunflower stars in the deep cold water of the British Columbian fjords.
We’ve heard of sunflower star survival at depth and have even heard of some sunflower stars being taken in prawn traps. Please be on the lookout for new sunflower stars and adult survivors on your dives. This may be our last chance to spot sunflower stars in the wild, or with any luck a happy return of our sunflower star friends.
