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Sunflower Seastar Now Critically Endangered

In August of 2020 the IUCN officially declared the Sunflower Seastar (Pycnopodia helianthoides) as critically endangered, one step before extinction.

It is easy to think of large predators like Killer Whales or Great White Sharks as being important predators for marine ecosystem. These large charismatic animals draw attention as they stalk and dramatically kill their prey. It’s easy to appreciate their large role in an ecosystem because we can visually see them making those changes. It may be challenging to imagine the importance of a seastar if you’re unfamiliar with this particular one. The Sunflower Seastar ranges from Baja to the Aleutian Islands and prays on a large number of invertebrates depending on its location. These predators can reach up to a meter long and have up to 24 arms. As they hunt along these rocky reefs engulfing various invertebrates they give off a scent that causes anything small enough for them to eat to hide. Much like a shark these veracious predators not only alter ecosystems by the amount of prey they consume but also by changing the behavior of there prey. One example of this is the Purple Urchin, one of the Sunflower Seastars favorite meals here in Northern and Central California. When the Purple Urchin senses the presence of the Sunflower Seastar it stops grazing on kelp and hides in rocky holes. This phenomenon has been well documented and has been quantified to show that when a Sunflower Seastar is present it not only controls the Purple Urchin populations but also decreases the amount of grazing that the urchins performs which creates a larger amount of kelp.

Unfortunately this key predator is no longer performing this vital role. According to a new study through Oregon State University the Sunflower Seastar has seen a 90.6% decline since 2013 due to a novel seastar wasting disease that has devastated populations for the last 7 years. Many reefs along the California coast are experiencing dramatic shifts from once healthy kelp forests to rocky reefs inhabited by dense populations of starving urchins consuming any new kelp before it can recover. This ecosystem shift was result of more than just the fall of the Sunflower Seastar, but its demise is an important lesson on how interconnected and fragile our ecosystems truly are.

Shepard, A., & Shepard, A. (2020). “‘Pycnopodia helianthoides’”, The Sunflower Star. 8235.


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