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• California Sandcastle Worm, Phragmatopoma californica 
  • Where: Santa Cruz County, California
  • When: October 2020
  • iNaturalist Post

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This week’s post was inspired by this repeating pattern I’ve seen recently while tidepooling, but hadn’t investigated yet. The culprit/artist/architect is the California Sandcastle Worm! Also known as the ‘honeycomb worm,’ or ‘honeycomb tube worm,’ you can find this interesting creature from mid to North California down to Baja California.

So how do they make this repeating pattern? Well there is power in numbers! What better way than to live in a colony! This colony was exposed during a low tide cycle, in a sheltered side channel, and covered an area about four feet in length, and perhaps two to three feet in width. This was not the only colony in the section of tidepools I was exploring. For the photos of the actual worm (below), this was at a different location, about 20 miles away, in a much sandier tide pool habitat.

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As the tide recedes the worms conceal themselves down in their tubes. But oooo when that tide comes back, those gorgeous lavender colored tentacles come out to catch a meal. Not only is food particles captured, but sand also! The sand grains are sorted to fit the needs of the tube, to fill holes or build upon the existing tube. The remaining sand grains are tossed out, tootles!

One of the local marine queens, Allison J. Gong wrote a piece in Bay Nature which explains the physiology of the sand castle worm extraordinarily well. While I’m often fascinated by poop, scat, and have way too many photos of it on my phone, I’ll leave the description of  this creatures poop and discarding methods to Allison. If “fecal pellets” sound interesting to you with fantastic corresponding photos, go and give it a read here, after this post of course.

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But how do these oodles of sand stay put together? Glue of course! But the complexities of glue that is both formed and set underwater is no small feat. Hence why researchers at University of California, Santa Barbara studied and successfully replicated this magnificent natural product. Zhao et al. discovered the glue is comprised of specific sequence of proteins with opposing charges. If interested this Wiki article dives deeper into the glue’s chemistry, much better than I could re-phrase.

Besides forming microarchitectural abodes, this glue could have medical applications such as repairing tissues or shattered bones, but also has non-biological applications too. Glue that works in the rain or underwater sounds like something I’d love to have in my backpacking toolkit.

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If you find yourself exploring California beaches or intertidal zones, try to find these beautiful structures. Worms are cool!

Resources

• Allison J. Gong’s Article in Bay Nature, Meet a Beach Worm That Builds Sand Castles
• iNaturalist “About” Page / Wiki Page Phragmatopoma-californica
• “Sandcastle worms teach us how to make underwater glue” by Futurity
• “Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange” by Zhao et al. in Nature
• “Sandcastle worms serve as inspiration for a new type of underwater adhesive being developed” by Sonia Fernandez on Phys.org