Sunflower Stars: Rulers of the Reef

Back in the day, I ran some experiments looking at different California kelp forest predators and their effects on trophic cascades. It was a fun time, doing things like banding Cancer crab claws and then watching how they still pinned down kelp crabs like a boss, making them run away in fear. But there was one predator I tested that stunned me, and, welp, made me a little fearful.

The sunflower star, Pycnopodia heliantoides.

I thought these big multi-armed beasts were pretty neat, but, then I watched one engulf a softball-sized red urchin (and that’s softball before the big spiky spines), and a day or so later, spit out all of the hard parts. Not sated, it then ate all of the purple urchin in the tank. Basically, it was a remorseless eating machine.

Couple this with a few old-marine-biologist’s tales of giant man-sized Pycnos and tales of their wandering off into the deep, with no ability to track them, and you can see why it took me a bit to conquer my fear of them for my usual profile picture.

 

Now, shows me that, um, I might have been right.

Sure, we know that they can hoover up reefs of tiny sea cucumbers, or affect smaller purple urchin barrens, but Burt et al. show that Pycnos have an impact that is even stronger than otters! Even cooler, they discovered this due to two simultaneous natural experiments – otters moving back into a historic part of their range (which they’d been hunted out of, so, natural?) combined with sea star wasting disease wiping out Pycnos a few years after. I’ll let their video explain even better.

For me, this work was deeply personal. My own early work tried to think about how a post-otter California was able to avoid the devestating consequences of their loss seen in the Aleutians. I always viewed Pycnos and the other predators as mere redundant species, with many of those predators being necessary to equal the raw force of otters. Burt et al. are really breaking the paradigm here, showing that while otters are absolutely key, that diversity still matters. Because the real urchin horf-master of the deep is Pycnopodia. All hail!

Also, as an added reward from the dive team, everybody dance now!

References

Burt, J.M., Tinker, M.T., Okamoto, D.K., Demes, K.W., Holmes, K., Salomon, A.K., 2018. Sudden collapse of a mesopredator reveals its complementary role in mediating rocky reef regime shifts. P Roy Soc Lond B Bio. 285, 20180553. doi:10.1098/rspb.2018.0553

Byrnes, J., Stachowicz, J.J., Hultgren, K.M., Randall Hughes, A., Olyarnik, S.V., Thornber, C.S., 2006. Predator diversity strengthens trophic cascades in kelp forests by modifying herbivore behaviour. Ecol. Lett. 9, 61–71. doi:10.1111/j.1461-0248.2005.00842.x (aw, my first dissertation chapter! wudda!)

Jarrett Byrnes (21 Posts)

Jarrett Byrnes is an Assistant Professor of Biology at the University of Massachusetts, Boston where he studies kelp forests and salt marshes. He earned his Ph.D. at UC Davis working at the Bodega Marine Lab studying the consequences of losing predator diversity in the sea. He loves cooking, and recommends trying to make bacon dashi: put two rinced pieces of kelp (~6") in 8 cups water. Heat to a boil and turn off. Steep for 10-15 min (depending on how kelpy you like it). Remove kelp, add 3/4 lb smoky bacon. Simmer 30 minutes. Add mirin, soy sauce, sake as needed for flavor. Let cool and refrigerate. Skim off fat. Now you have an amazing base to cook fingerling potatoes and clams in. Top with chopped crispy bacon and green onions (or pureed with oil). And for, well, everything else. (Adapted from the Momofuku recipe)


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3 comments to “Sunflower Stars: Rulers of the Reef”
  1. To be able to eat a softball-sized red urchin is crazy, just how big can these stars get? Maybe, just maybe they could get to me man-sized!! Awesome.

  2. Most starfish have semi-rigid skeleton, but there are many different elements on the skeleton of the sunflower star. They allow you to open the mouth of the surah, its body gets bigger and gets a bigger hunt. Thanks for sharing such an awesome content.

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