A Sea of Glass Page 14
Another impact of a changing ocean is the spread of diseases that normally wouldn’t survive in cooler waters. Until recently, this kind of emerging catastrophic epidemic was documented best with terrestrial species, primarily amphibians. Over the past two decades, more than one hundred species from around the world have been extirpated by a commonly occurring fungus that was once non-lethal (Pounds et al. 2006). However, as conditions changed, this fungus morphed into a deadly parasite, leaving rain forest rivers and High Sierra lakes filled with the fungus-ridden bodies of dead frogs. Scientists watched whole populations disappear overnight (Crawford et al. 2010).
We are also now seeing entire marine species diminished by pathogenic microbes. As I discussed in chapter 7, we are currently living through the sad story of a mass viral epidemic decimating over twenty species of West Coast sea star, stretching from Alaska to Mexico (Hewson et al. 2014). Although we’re still working out the full story of what triggered this massive sea star epidemic, all evidence points to elevated temperatures and other stressors increasing the susceptibility of sea stars to a viral disease (Eisenlord et al., in review).
It is fair to conclude that the industrialization driven by fossil fuels is the root of most of the evils plaguing our ocean biodiversity. First, it has fueled the massive industrialized fishing fleets that have decimated fish populations on our coastlines and scoured the furthest reaches of our oceans (Ponti et al. 2014; McCauley et al. 2014). Second, it has put greenhouse gases into both the oceans and the atmosphere. Both over-fishing and carbon pollution seem like huge, insoluble problems that have no borders. They are not. For species ranging from East Coast cod to sharks in Hawaii and Asia, new fisheries policies are rapidly preventing a spiral into extinction. This year nine U.S. states passed new laws outlawing the finning and even possession of any shark products. We hope the rest of the world will follow.
In contrast to most of my publications, there is only one graph in this book (page 165). It depicts the projected future scenario of CO2 emissions and shows quite clearly the problem we have with inertia. RCP 8.5 is the trajectory we are currently on, and it will lead without question to massive ocean extinctions in the next fifty years, as well as untold human misery due to increased storms, rising sea levels, and increased sickness. RCP 2.6 represents one plot of hope, the chance to avert the worst of the catastrophe if we act immediately. Even under this hopelessly optimistic scenario, it would still take until 2050 to begin to dial back emissions levels. Under any of these scenarios, we face big impacts in the next fifty years.
° ° °
Fixing the carbon dioxide problem is tricky because it requires such a large and concerted global effort and its effects are played out over long time spans that are hard for us to grasp given the average human life expectancy. Most of my college students were born in the years 1992–1996 and will be over sixty before CO2 levels would begin to drop under the most ambitious, optimistic projections. If we think outside the box, we might be able to do better. We have reached the point where we need not only to reduce our emissions, but also to reduce existing carbon dioxide levels. There is interest now in carbon-reduction methods such as bioenergy with carbon capture and storage. One of the possible solutions for renewable, non-carbon-based energy comes from the oceans. Consider the miracle of biofuels from solar-powered marine algae that require no freshwater and, if their use is properly designed, can also capture carbon and remove it from the atmosphere (Greene et al. 2010). I consider the hopefulness of human ingenuity as I explore the vivid tapestry of soft and precious corals carpeting the underwater cliffside in Liguria, still unmolested by these so-called wicked problems.
This entire dive in the marine preserve tucked at the top of the Italian boot has been a fairyland of Mediterranean biodiversity, including bountiful fish, from tiny, sparkling plankton-eaters to huge, looming groupers. Although our ocean biodiversity is as fragile a legacy as our Blaschka glass, this place reminds me there is so much we can do to chart a more positive future. I can feel Leopold nodding gravely in satisfaction at seeing how his stunning glass has persisted through times of neglect to emerge as an inspiration to protect the sea animals he loved. I hope we will act to preserve the staggering ocean biodiversity still on our planet.
Projected effects of four different emission reduction scenarios on atmospheric CO2 concentration and mean global temperature. The scenarios, calculated in 2010, show business as usual (BAU), in which the emission rate rises so that by 2100 it increases 500 percent relative to the 2005 rate; aggressive reduction (AR), in which the emission rate begins to decline in 2015 and reaches 20 percent of the 2005 rate in 2050; very aggressive reduction (VAR), in which the emission rate begins to decline in 2015 and reaches zero in 2050; and impossibly aggressive reduction (IAR), in which the emission rate drops to zero immediately. This last scenario is the only one that keeps temperature increases below 2°C up to 2100. (Adapted with permission from Greene et al., 2010)
ACKNOWLEDGMENTS
THIS IS MY first book, and it did take a village of wonderful people to help make it a reality. The book was inspired by my continued wonder at the Blaschka masterpieces and the adventure of finding the living matches. The best gift is the continuing collaboration with David Brown, both through the writing of this book and through his Fragile Legacy film project, as well as in the epic quest that the Blaschkas have sent us on. I also owe great thanks to Jeff Del Viscio, who embraced the early days of our quest and collaborated in producing a rather stunning New York Times animated piece.
My son, Nathan, and daughter, Morgan, patiently read early chapters and advised how to make them more readable. From the outset, Morgan pushed me to share my story rather than catalogue scientific findings and facts. Nathan scrawled “show, don’t tell” all over my early drafts and reminded me repeatedly that chapters needed to build toward some kind of payoff for the reader. Merrik Bush-Pirkle at the University of California Press helped with almost every word and showed me how to set up what payoffs there were. Merrik’s steady patience, creativity, and deep insight about good writing structure have been huge gifts in this process. I am grateful also to Blake Edgar for his consistent help and enthusiasm, and to Claudia Smelser for her magic in crafting composite figures. Reyn Yoshioka, Cornell honors student turned lab coordinator and book assistant, helped with every chapter, did a lot of fact-checking, and contributed some amazing photographs. Reyn’s attention to detail and passion for the project were epic. He patiently checked and found new references, triple-checked and updated species names, and emailed the second he found a new Blaschka match.
I am grateful to the Corning Museum of Glass for our long partnership, beginning with its safe storage of our collection, and to Jim Galbraith in the Rakow Research Library for graciously sharing images of the watercolors. I look forward to our shared endeavor to display Cornell’s collection of Blaschka pieces at the Corning Museum. Warm thanks to Karel Wight, Audrey Whitty, Warren Bunn, Lori Fuller, and Marv Bolt. Cornell’s Atkinson Center for a Sustainable Future (ACSF) and the Corning Foundation provided funds for the film Fragile Legacy, thus helping to defray the costs of our research trips. I am grateful to ACSF director Frank DiSalvo and to Lauren Chambliss for their enthusiasm and help. I am grateful to Paul Feeny for his initial impulse to launch our Blaschka project, and to him and Mary Berens for financial help with our collection. I thank Susan Syversen for her help in restoring our common octopus and several other models. I thank all our donors for their contributions toward restoring our collection and Elizabeth Brill for her brilliant work with our models.
The other members of my village are fellow scientists who filled in correct details of taxonomy and ecology. Jim Morin offered his systematic and invertebrate expertise and helped in the initial effort to update to the current names. A wonderful group of colleagues read early versions of chapters: Sara Lindsey, Rachel Merz, and Sarah Woodin helped with worms, Claudia Mills with jellyfish, Morgan Mouchka and Megan Dethier with anemones, Rich
ard Strathmann and Morgan Eisenlord with echinoderms, Brian Penny with nudibranchs. Charles Greene helped with the concluding chapter. Allison Tracy commented on several chapters but helped most (in the eleventh hour!) with the concluding chapter and the appendix. John Pearse and Peter Sale read the entire book and contributed enthusiasm and many helpful suggestions. Thanks to Harry Greene for being my “book buddy” and encouraging and advising me about early stages of the writing and publishing process, and to Thor Hansen for advice along the way. Finally, I thank my husband, Charles Greene, for so many discussions about themes in this book, for pitching in to read chapters when I really needed help, and for giving me Haeckel’s Art Forms in Nature—but most of all, for patiently encouraging my two-year obsession with writing this book.
APPENDIX
A Primer on the Blaschka Tree of Life
The tree of spineless life, rendered in Blaschka glass.
THE OCEAN IS the cradle of life, housing the greatest diversity of living organisms on the planet. When I look at the sea, I imagine it roiling underneath with all the invertebrates, fish, and whales that occupied it hundreds of years ago. It would look just like one of the Philip Henry Gosse prints of tide pools packed with all colors, shapes, and sizes of sea anemones, or one of Ray Troll’s ocean fish prints (www.trollart.com). In this appendix, I introduce relationships in the ocean’s tree of life, the backstory that will link my larger quest to find our star actors. Who was that first, most ancient of invertebrates, and who is its closest relative? Do we humans have any relatives among the Blaschka masterpieces? What are sea slugs anyway, and what is the link within the molluscs between sea slugs and octopuses?
Our Blaschka collection is made for telling this story, since we have representatives from most of the branches on this animal tree of life, and some pretty amazing detail on the twigs. It’s possible that when I say “tree of life” you imagine a tree dominated by zebras, lions, gazelles, humans, and turtles. Wonderful though those animals are, they are only twigs on one very small branch, the Vertebrata (meaning animals with backbones), that sits very far from the base of the tree. Being very far from the base means having evolved relatively recently in evolutionary time.
It’s the base of the tree and the lower branches that count the most in showing us ancient body plans. The tree’s base is dominated by our spineless wonders, all the animals without backbones that reveal the time-tested forms of life. This is where all the evolutionary action was, and maybe still is. In our introductory evolutionary biology course at Cornell University, our complete tree of life includes all life on the planet, from viruses and bacteria to bigger things called eukaryotes, which are plants and animals with a membrane around the nucleus in each cell. On that complete tree of life, all animals—from sponges to humans—are only one branch amid twenty-six. For this book, I’ve zoomed in on the base of this animal branch.
If you look on the internet, you will see many trees of life, some of which are quite complicated and don’t look anything like trees. I’m telling a simpler story in this book, but it is correct and up to date in its details. Like a living tree, our reconstruction of animal relationships is constantly changing as we continue to discover new life and redraw taxonomic relationships as new information emerges.
A Sea of Glass sculpts, with the Blaschkas, a tree of spineless life. This to me is the most beautiful of all art—the epic picture of our animal biodiversity, the most ancient of all roots. For hundreds of years, scientists have puzzled over the relationships shown in the illustration on page 170, assembling and reassembling the lineages in the tree. What was the first animal? What is the most ancient body plan? Who branched from that first one and when? How do they all fit together? What is the pattern of extinction and subsequent diversification through the history of time? Can we find all the pieces to solve this puzzle before the increasing pace of extinction, which has finally reached the oceans, overwhelms us?
Scientists divide the tree of life into large groups, or phyla, of related animals or plants. Each phylum is distinguished by some uniformity of body plan. For example, within the phylum Echinodermata, all animals have fivefold symmetry, showing up as five arms on the sea star and brittle star and five rows of tiny tube feet on the sea cucumber. Echinoderms are also united by deep, shared secrets in their embryonic development, and this links them even to our human phylum, Chordata. This primer shows the larger branches on the tree of spineless life, the phyla, and how the subdivisions, the classes, fit within them. For example, sea cucumbers, sea stars, brittle stars, and sea feathers are all classes within the phylum Echinodermata. Similarly, cephalopods and gastropods are classes within the phylum Mollusca. Cornell’s Blaschka collection has approximately 569 glass invertebrate models, which makes it the largest Blaschka animal collection in the world. The Blaschkas focused the most effort in showing the diversity within two phyla: more than 440 models are either a cnidarian (227) or a mollusc (214). These include the anemones and relatives (130 sculptures), the sea jellies and relatives (71 sculptures), the sea slugs (137 sculptures), and the octopuses and cuttlefish (38 sculptures). But the Blaschkas’ reach embraces more than the cnidarians and molluscs and spans much of the spineless tree of life, including approximately 22 annelid worms, 45 echinoderms, 25 chordates, and a dozen animals from other minor taxa. If there are a few branches missing from our Cornell collection, we can fill them in from the 800 different glass animals the Blaschkas made that are scattered around the world in other collections. It is also enlightening to consider some of the very interesting gaps and missing branches in the Blaschka collection, since their omission also tells a story.
The Blaschkas drew from many of the branches for their glass models, although the focus of their effort was to depict softbodied animals, such as jellyfish, anemones, sea slugs, octopuses, and worms. The Blaschkas wanted to create, in glass, those spineless animals that could not be easily seen by people. For example, a crab is hard bodied and can be easily preserved, but an octopus or jellyfish loses its distinctive shape and color when it dies, and it can’t be stuffed like a mountain lion or badger. But I am getting ahead of myself; let’s start at the beginning. Which animal is the most ancient, and do we have a model to show it?
SPONGES
Sponges, the phylum Porifera, have long been considered by many biologists to be the most ancient of animals. They are distinguished by special cells called choanocytes that are both pumps that move water and food filters deep in the chambers of a sponge. They are a trick of nature, instrumental in an animal that works well with no tissues or organs and only a collection of cells. Biologists view sponges as the key to understanding how tiny, unicellular organisms propelled by thread-like flagellae aggregated to form the first multicellular animal, which might have looked like a sponge. We no longer have a single sponge in our collection, but the collections at the Natural History Museum of Ireland, in Dublin, and the Museum of Comparative Zoology at Harvard University have models of a Mediterranean sponge.
CTENOPHORES
With the advent of DNA sequencing, the relationships in the tree of life are constantly being rewritten, so even the most basic question, “Which is the first branch?” is not settled. For instance, until recently, scientists like myself believed that sponges were the most basal branch of animals. However, a groundbreaking study first published in 2013 (Ryan et al. 2013; Moroz et al. 2014) nudges sponges aside. The prize of earliest branch in the tree of life now goes to the comb jellies, in the phylum Ctenophora. Comb jellies are distinguished by having a special adhesive cell called a colloblast, used to capture tiny plankton, and rows (or combs, hence their name) of iridescent cilia for propulsion. It is exciting that its ancestry as one of the oldest animals was confirmed in 2012 in work done at our own Friday Harbor Laboratories in the San Juan Islands. John Finnerty, professor of biology at Boston University, comments on the implications: “If the split between ctenophores and all other animals was the earliest split in animal evolution, it suggests some uni
ntuitive facts about evolution. . . . For example, that sponges, which are very simple animals that lack a nervous system and lack muscle cells, actually came from an ancestor (the ctenophores) that had those features” (Williams 2013). The Friday Harbor team made its discovery by extracting DNA from ctenophore embryos, sequencing the entire genome, and comparing it with whole genome sequences of twelve species from other animal phyla. Billie Swalla, director of Friday Harbor Labs, says, “We feel pretty confident that ctenophores are the sister group to the rest of the extant animals we studied and therefore the most basal living ancestor.” There are several ctenophores in Cornell’s collection, even though the Blaschkas could never have known, in 1868, that these represented the first branch on the animal tree of life.
Ctenophora: Hormiphora plumosa in glass. Photo by Kent Loeffler.
CNIDARIA
This phylum brings us to a close ctenophore relative, a giant phylum on the Blaschka tree of life that contains both the anemones and the jellyfishes. At 227 models, a big portion of our collection is made up of cnidarians. Both the beauty and the biological complexity of this group are dazzling, and it’s a daunting job to pick the most elemental characters and relationships. All the cnidarians are defined by having stinging capsules called nematocysts, described in detail in chapter 3. The stinging capsules are very similar in form and function to the ctenophore’s colloblasts, which secrete an adhesive (instead of a venom) for prey capture. The similarity in these capsules is more evidence for the close relationship between the cnidarians and ctenophores. The cnidarians come in two basic forms, either a medusa, also known as a jellyfish, or a polyp, also known as an anemone. They look vastly different, since the medusa floats and voyages the great oceans and the polyp sits rooted to the bottom and never goes anywhere.