Spirals in Time: The Secret Life and Curious Afterlife of Seashells

by Helen Scales

  Morphospecies A ‘probable’ species that appears different from others based on the way it looks (morphological characters) but has not been fully and formally identified.

  Nacre The shiny layer of a mollusc’s shell (usually on the inside). Also known as mother-of-pearl.

  Nautilid (Nautilida) A lineage of shelled cephalopods that first evolved in the Devonian period around 400 million years ago, leading up to the living chambered nautiluses.

  Nudibranch A group of shell-less marine gastropods also known as sea slugs. Their name means ‘naked gills’. Pronounced ‘nudie-brank’.

  Ocean acidification A reduction in the average pH of the oceans as a consequence of atmospheric carbon dioxide dissolving into seawater. The oceans have already become 30 per cent more acidic in the last 200 years.

  Pelagic Anything belonging to the realm of the open sea.

  Periostracum A layer of protein that covers the outside of a mollusc’s external shell.

  Phylum (plural phyla) Major category within the living world. Examples include molluscs, arthropods (crabs, shrimp, etc) and annelids (segmented worms). In turn, each phylum is traditionally divided up into classes, then orders, families, genera and species.

  Plankton Microscopic, aquatic drifting creatures including both phytoplankton (plants and algae) and zooplankton (animals).

  Pteropods An informal term for the gastropod orders Thecosomata (sea butterflies) and Gymnosomata (sea angels). These are pelagic snails that ‘fly’ underwater with little wings.

  Radula The mouthparts of most molluscs. They come in a huge range of shapes and arrangements, allowing molluscs to specialise in different diets, from general herbivory to highly specialised hunting.

  Sacoglossan A group of shell-less sea slugs that specialise in sucking sap from algae and plants.

  Scaphopods The small class of molluscs also known as tusk shells. They look like miniature elephant’s tusks, and generally live buried in seabed sediments.

  Sclerites Bristles found on some molluscs, including chitons, solenogastres, caudofoveates and the now-extinct Wiwaxia (although not everyone agrees Wiwaxia was a mollusc).

  Solenogastres An obscure class of molluscs. Like caudofoveates they are wormy and shell-free. They live either on the surface of mud or on corals.

  Spat A common term for settled bivalve larvae, especially oysters and mussels.

  Spondylus A genus of bivalve generally deep red, orange or purple in colour and covered in long spines that attract encrusting organisms (sponges, seaweeds, etc). Also known as thorny oysters.

  Taxonomy The branch of science that occupies itself with identifying and naming living things, and sorting out how they are all related to each other.

  Wiwaxia A creature from the Cambrian period around 520 million years ago, discovered in the Burgess Shale fossils. Some experts consider it to be an early mollusc. It had no shell but was covered in scales and bristles.

  Select Bibliography

  Chapter 1 Meet the Shell-makers

  Bouchet, P., Lozouet, P., Maestrati, P. & Heros, V. 2002. Assessing the magnitude of species richness in tropical marine environments: exceptionally high numbers of molluscs at a New Caledonia site. Biological Journal of the Linnean Society 75: 421–436.

  Johnson, S. B., Warén, A., Tunnicliffe, V., Van Dover, C., Wheat, C. G., Schultz, T. F. & Vfrijenhoek, R. C. 2014. Molecular taxonomy and naming of five cryptic species of Alviniconcha snails (Gastropoda: Abyssochrysoidea) from hydrothermal vents. Systematics and Biodiversity 1–18.

  Kocot, K. M. 2013. Recent advances and unanswered questions in deep molluscan phylogenetics. American Malacological Bulletin 31: 195–208.

  Ponder, W. F. & Lindberg, D. R. R. 2008. Phylogeny and Evolution of the Mollusca. University of California Press, Berkeley.

  Smith, M. R. 2014. Ontogeny, morphology and taxonomy of soft-bodied Cambrian ‘Mollusc’ Wiwaxia. Palaeontology 57: 215–229.

  Chapter 2 How to Build a Shell

  Boettiger, A., Ermentrout, B. & Oster, G. 2009. The neural origins of shell structure and pattern in aquatic mollusks. PNAS 106: 6837–6842.

  Clements, R., Liew, T.-S., Vermeulen, J. J. & Schilthuizen, M. 2008. Further twists in gastropod evolution. Biology Letters 4: 179–182.

  Gong, Z., Matzke, N. J., Ermentrout, B., Song, D., Vendetti, J. E., Slatkin, M. & Oster, G. 2012. Evolution of patterns on Conus shells. PNAS Early Edition DOI: 10.1073/pnas.1119859109

  Hoso, M., Kameda, Y., Wu, S.-P., Asami, T., Kato, M. & Hori, M. 2010. A speciation gene for left–right reversal in snails results in anti-predator adaptation. Nature Communications DOI: 10.1038/ncomms1133

  Meinhardt, H. 2009. The Algorithmic Beauty of Seashells. Springer, Dordrecht, Heidelberg, London & New York.

  Raup, D. R. 1962. Computer as aid in describing form in gastropod shells. Science 138: 150–152.

  Thompson, D’Arcy Wentworth. 1917. On Growth and Form. Cambridge University Press, Cambridge. Reprinted 1992.

  Vermeij, G. J. 1995. A Natural History of Shells. Princeton University Press, Princeton.

  Chapter 3 Sex, Death and Gems

  Bouzzouggar, A., Barton, N., Vanhaeren, M., d’Errico, F., Collcutt, S., Higham, T., Hodge, E., Parfitt, S., Rhodes, E., Schwenninger, J.-L., Stringer, C., Turner, E., Ward, S., Moutmir, A. & Stambouli, A. 2007. 82,000-year-old shell beads from North Africa and implications for the origins of modern human behavior. PNAS 104: 9964–9969.

  Claassen, C. 1998. Shells. Cambridge University Press, Cambridge.

  Gaydarska, B., Chapman, J.C., Angelova, I., Gurova, M. & Yanev, S. 2004. Breaking, making and trading: the Omurtag Eneolothis Spondylus hoard. Archaeologia Bulgarica 8: 11–33.

  Hogendorn, J. & Johnson, M. 1986. The Shell Money of the Slave Trade. Cambridge University Press, Cambridge.

  Chapter 4 Shell Food

  Diaz, R. J. & Rosenberg, R. 2008. Spreading dead zones and consequences for marine ecosystems. Science 321: 926–929.

  Glibert, P. M., Anderson, D. M., Gentien, P., Granéli, E. & Sellner, K. G. 2005. The global, complex phenomenon of Harmful Algal Blooms. Oceanography 18: 136–147.

  Potasman, I. & Odeh, M. 2002. Infectious outbreaks associated with bivalve shellfish consumption: a worldwide perspective. Clinical Infectious Diseases 35: 921–928.

  Richter, C., Rao-Quiaoit, H., Jantzen, C., Al-Zibdah, M. & Kochzius, M. 2008. Collapse of a new living species of giant clam in the Red Sea. Current Biology 18: 1349–1354.

  For online advice on making better seafood choices:

  Monterey Bay Aquarium Seafood Watch, www.seafoodwatch.org

  Marine Conservation Society Fishonline, www.fishonline.org

  Australia’s Sustainable Seafood Guide, www.sustainableseafood.org.au

  Chapter 5 A Mollusc Called Home

  Beck, M. W., Brumbaugh, R. D., Airoldi, L., Carranza, A., Coen, L. D., Crawford, C., Defeo, O., Edgar, G. J., Hancock, B., Kay, M. C., Lenihan, H. S., Luckenbach, M. W., Toropova, C. L., Zhang, G. & Guo, X. 2011. Oyster reefs at risk and recommendations for conservation, restoration, and management. Bioscience 61: 107–116.

  zu Ermgassen, P. S. E., Spalding, M. D., Grizzle, R. E. & Brumbaugh, R. D. 2013. Quantifying the loss of a marine ecosystem service: filtration by the eastern oyster in US estuaries. Estuaries and Coasts 36: 36–43.

  Haires, D. 2013. The flame shells of Kyle Akin. Mollusc World 32: 15–17.

  Kirby, M. X. 2004. Fishing down the coast: historical expansion and collapse of oyster fisheries along continental margins. PNAS 101: 13096–13099.

  Laidre, M. E., Patten, E. & Pruitt, L. 2012. Costs of a more spacious home after remodelling by hermit crabs. Journal of Royal Society Interface DOI: 10.1098.

  Lewis, S. M. & Rotjan, R. 2009. Vacancy chains provide aggregate benefits to Coenobita clypeatus hermit crabs. Ethology 115: 356–365.

  Chapter 6 Spinning Shell Stories

  Hendricks, I. E., Tenan, S., Tavecchia, G., Marbà, N., Jordà, G., Deudero, S., Álvarez, E. & Duarte, C. M. 2013. Boat anch
oring impacts coastal populations of the pen shell, the largest bivalve in the Mediterranean. Biological Conservation 160: 105–113.

  Maeder, F. 2008. Sea-silk in Aquincum: first production proof in antiquity. Purpureae Vestes. II Symposium Internacional sobre Textiles y Tintes del Mediterráneo en el mundo antiguo (eds C. Alfaro & L. Karali), pp. 109–118.

  McKinley, D. 1998. Pinna and her silken beard: a foray into historical misappropriations. Ars Textrina 29: 9–223.

  Project Sea-silk website: www.muschelseide.ch/en

  Chapter 7 Flight of the Argonauts

  Broderip, W. J. 1828. Observations on the animals hitherto found in the shells of the genus Argonauta. The Zoological Journal 4: 57–66.

  Finn, J. K. & Norman, M. D. 2010. The argonaut shell: gas-mediated buoyancy control in a pelagic octopus. Proceedings of the Royal Society B: Biological Sciences 277: 2967–2971.

  Hewitt, R. A. & Westermann, G. E. G. 2003. Recurrences of hypotheses about ammonites and argonauta. Journal of Paleontology 77: 792–795.

  Kruta, I., Landman, N., Rouget, I., Cecca, F. & Tafforeau, P. 2011. The role of ammonites in the Mesozoic marine food web revealed by jaw preservation. Science 331: 70–72.

  Landman, N. H., Goolaerts, S., Jagt, J. W. M., Jagt-Yazykova, E. A., Machalski, M. & Yacobucci, M. M. 2014. Ammonite extinction and nautilid survival at the end of the Cretaceous. Geology DOI: 10.1130/G35776.1

  Chapter 8 Hunting for Treasures

  Barord, G. J., Dooley, F., Dunstan, A., Ilano, A., Keister, K. N., Neumeister, H., Preuss, T., Schoepfer, S. & Ward, P. D. 2014. Comparative population assessments of Nautilus sp. in the Philippines, Australia, Fiji, and American Samoa using baited remote underwater video systems. Plos ONE 9: DOI: 10.1371/journal.pone.0100799

  Dance, S. P. 1986. History of Shell Collecting. E. J. Brill, Leiden.

  De Angelis, P. 2012. Assessing the impact of international trade on chambered nautilus. Geobios 45: 5–11.

  Reeve, L. A. & Sowerby, G. B. 1843–1878. Conchologia Iconica, or Illustrations of Shells of Molluscous Animals. Lovell Reeve, London.

  Chapter 9 Bright Ideas

  Finnemour, A., Cunha, P., Shean, T., Vignolini, S., Guldin, S., Oyen, M. & Steiner, U. 2012. Biomimetic layer-by-layer assembly of artificial nacre. Nature Communications 3: DOI: 10.1038/ncomms 1970

  Kohn, A. J. 1956. Piscivorous gastropods of the genus Conus. Zoology 42: 168–171.

  Li, L. & Ortiz, C. 2014. Pervasive nanoscale deformation twinning as a catalyst for efficient energy dissipation in a bioceramic armour. Nature Materials 13: 501–507.

  Mirkhalaf, M., Dastjerdi, A. K. & Barthelat, F. 2014. Overcoming the brittleness of glass through bio-inspiration and micro-architecture. Nature Communications DOI: 10.1038/ncomms4166

  Olivera, B. M. & Cruz, L. J. 2001. Conotoxins, in retrospect. Toxicon 39: 7–14.

  Peters, H., O’Leary, B. C., Hawkins, J. P., Carpenter, K. E. & Roberts, C. M. 2013. Conus: first comprehensive conservation Red List assessment of a marine gastropod mollusc genus. Plos ONE 8: DOI: 10.1371/journal.pone.0083353

  Seronay, R. A., Fedosov, A. E., Astilla, M. A., Watkins, M., Saguil, N., Heralde III, F. M., Tagaro, S., Poppe, G. T., Aliño, P. M., Oliverio, M., Kantor, Y. I., Concepción, G. P. & Olivera, B. M. 2010. Biodiverse lumun-lumun marine communities, an untapped biological and toxinological resource. Toxicon 56: 1257–1266.

  Winter, A. G., Deits, R. L. H., Slocum, A. H. & Hosoi, A. E. 2014. Razor clam to RoboClam: burrowing drag reduction mechanisms and their robotic adaptation. Bioinspiration & Biomimetics 9.

  Yao, H., Dao, M., Imholt, T., Huang, J., Wheeler, K., Bonilla, A., Suresh, S. & Ortiz, C. 2010. Protection mechanisms of the iron-plated armor of a deep-sea hydrothermal vent gastropod. PNAS 107: 987–992.

  Chapter 10 The Sea Butterfly Effect

  Bednarsek, N., Feely, R. A., Reum, J. C. P., Peterson, B., Menkel, J., Alin, S. R. & Hales, B. 2014. Limacina helicina shell dissolution as an indicator of declining habitat suitability owing to ocean acidification in the California Current Ecosystem. Proceedings of the Royal Society B: Biological Sciences 281.

  Caldeira, K. & Wickett, M. E. 2003. Anthropogenic carbon and ocean pH. Nature 425: 365.

  Comeau, S., Gorsky, G., Alliouane, S. & Gattuso, J.-P. 2010. Larvae of the pteropod Cavolinia inflexa exposed to aragonite undersaturation are viable but shell-less. Marine Biology 157: 2341–2345.

  Gattuso, J.-P. & Hansson, L. 2011. Ocean Acidification. Oxford University Press, Oxford.

  Gattuso, J.-P., Mach, K. M. & Morgan, G. 2013. Ocean acidification and its impacts: an expert survey. Climatic Change 117: 725–738.

  Gazeau, F., Parker, L. M., Comeau, S., Gattuso, J.-P., O’Connor, W. A., Martin, S., Pörtner, H. & Ross, P. M. 2013. Impacts of ocean acidification on marine shelled molluscs. Marine Biology 160: 2207–2245.

  Lalli, C. M. & Gilmer, R. W. 1989. Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks. Stanford University Press, Stanford.

  Lischka, S., Büdenbender, J., Boxhammer, T. & Riebesell, U. 2011. Impact of ocean acidification and elevated temperatures on early juveniles of the polar shelled pteropod Limacina helicina: mortality, shell degradation, and shell growth. Biogeosciences 8: 919–932.

  Acknowledgements

  Turning my attention from a single, obscure genus with 40 or so species to an entire, globe-spanning phylum containing hundreds of thousands of motley creatures was, perhaps, a bold move. Writing about seashells and molluscs has been an altogether different experience compared to exploring the world of seahorses and luckily a lot of wonderful people have been there to help me navigate these broad, rambling reaches of the animal kingdom.

  I am deeply grateful to all the researchers who have shared with me their molluscan enthusiasms and ideas, answered my questions and helped me make fewer mistakes than I would have on my own (any slip-ups that are still in the book are entirely down to me). Thank you to Philippe Bouchet, Martin Smith, Reuben Clements, Thor-Seng Liew, Bard Ermentrout, George Oster, Masaki Hoso, Bisserka Gaydarska, Dan Harries, Philine zu Ermgassen, Piero Addis, Vicky Peck, Nina Bednaršek, Gareth Lawson, Julian Finn, Ken McNamara and Baldomero Olivera.

  It was a great honour to be granted a Roger Deakin award for this book from the Authors’ Foundation at the Society of Authors. This gave me a link to one of my favourite and much-missed nature writers and allowed me to carry out a series of research trips. My hunt for sea-silk in Sardinia would not have been possible, or nearly as much fun, if it weren’t for Alessandro Spiga and Silvia Messori, who so warmly welcomed me into their home, took me snorkelling to see Noble Pen Shells and introduced me to Chiara Vigo. Thank you also to Annelise Hagan and Eleonora Manca for putting me in touch with the people of Sant’Antioco, to Rebecca Lewis for coming along on our adventure and translating for me, and to Chiara for showing me her work. My sea-silk story would have been impossible without the kindness and knowledge of Felicitas Maeder, especially for introducing me to the people at Archeotur in Sant’Antioco. My thanks in particular go to Ignazio Marrocu, Giustino Argiolas and Patrizia Zara, and of course to Giuseppina and Assuntina Pes for inviting me into their home and demonstrating their sea-silk skills.

  I am hugely grateful to Ulf Riebesell for inviting me to join him in Gran Canaria, and to the rest of the BIOACID team who kindly took me out to Gando Bay to see the KOSMOS mesocosms and let me snoop around their labs. A very special thanks goes to Silke Lischka for so graciously helping me find sea butterflies and sharing her immense enthusiasm for these tiny creatures when she really should have been sleeping and recovering from the gruelling research schedule.

  In the UK, a big thank you to fellow Triton fan Andy Woolmer for showing me around the Mumbles, and for all his insights into oysters, whelks, cockles, mussels and the rest (and for persuading me to try winkles for the first time). Thank you to Jon Ablett for showing me behind the scenes at London’s Natural History Museum, and to Peter Dance for our discussions, beginning several years ago, about Hugh Cuming, for shari
ng his Cuming archive with me, and for treating me to the best Thai clams I’ve ever tasted. A warm thank you to Fatou Janha and all the women of the TRY Oyster Women’s Association in The Gambia. If you visit The Gambia, make sure you try the oysters.

  This book wouldn’t have happened without Jim Martin at Bloomsbury, who has been the ideal combination of editor and molluscan co-conspirator. Many thanks to him for indulging and sharing my shelly whims, and for being so utterly selfless in the face of many edible molluscs. Our journey to the book’s cover and illustrations began when I spotted a beautiful drawing of an argonaut on Aaron John Gregory’s website. When I discovered that Aaron is not only a talented artist but also as much of a marine geek as me, I instantly knew that he was our man. A huge thank you to Aaron for his immense patience and hard work, and for so brilliantly bringing the molluscs to life.

  Lastly I want to thank all my dear friends and family who have cheered me on through my seashell adventures, who have read my words, sat through all the shell stories, and in many ways kept me going. My love and gratitude go to you all, and in particular to Anna Petherick, Riamsara Kuyakanon Knapp, Eric Drury, Matthew Wilkinson (whose book on animal locomotion was being written at the same time as this one), Ria and Jake Snaddon (plus baby Snaddon who will arrive in the world shortly before this book does, and who I look forward to showing seashells in the years ahead), Peter Wothers, Umut Dursun, Conor Jamieson, Liam Drew, Joshua Drew, Drew Bednarski and Meghan Strong, Kate Lash (my official geochemistry consultant), and finally my parents, Di and Tom Hendry, my mum especially for coming up with the book’s inspired subtitle, and my dad for reading so much of the manuscript when he should have been working on his Ph.D. And Ivan, my constant companion in life and words, who calls me up on my smutty jokes, finds ways to help me tell my stories, and always makes things better.

  Index

  abalone 111