A Sea of Glass Page 8
Serpula vermicularis in glass (left) and a Blaschka watercolor. This species is circumglobal and is commonly seen in both the Atlantic and Pacific. Photo by David O. Brown; watercolor courtesy of the Rakow Research Library, Corning Museum of Glass, BIB ID: 95570.
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Back at our mudflat, the tide is beginning to take back the coastline, reducing our range to a narrow ribbon. We are now up to seven different types of worm, but I want one more. I want the Blaschkas’ serpulid worm, with its bright feather duster crown of tentacles and the trapdoor that closes off its calcareous tube. We found its tiny cousin, the two-millimeter-long spirorbid worm, with bright red tentacles and operculum, living by the hundreds on rocks and algae, filtering plankton with its powerful ciliated tentacles. It’s now 10:00 a.m., the point at which the students are usually pushing to explore the historic Creek Farm building in search of a warm breakfast and showers. This mud-encrusted group, some of them splattered from head to toe and sporting mud sculpture on their faces, refuses to leave the hunt and keeps digging, hoping to find one more new worm. Finally, the rising tide drives us off the beach, and after a successful breakfast and long, hot, showers (the first non-navy shower in weeks) we tramp back to the boat for our return to Appledore Island.
As the others load up, Reyn, Courtney, and I crouch down and reach underneath the dock to pull up handfuls of critters to see what new ones we can find. Our yield is a bucket packed with anemones, mussels, feather worms, sea squirts, all abundant here, and crawling with even more new families of worms. Best of all, we find a few bright-colored sea slugs that are perfect Blaschka matches. And then, tucked so tightly in among the mussels that we almost missed it, is our long-awaited prize of the day: the serpulid tubeworm, a perfect match to our glass figure (page 84). It doesn’t look like much pulled into its tube, with the trapdoor shut, but we celebrate the long hard hunt for a species we thought would be common. We climb into the boat, still muddy but pleased that in this moment, the fate of this vast and diverse group of unobtrusive invertebrates is better than expected.
5.
SEA SLUGS
Fire Stealers of the Deep
Spotted sacoglossan (Caliphylla mediterranea) in glass. We didn’t find this very small sea slug, but it has been recorded within the past two decades on other checklists, including that of Riccardo Cattaneo-Vietti and Ferdinando Giovine (Cattaneo-Vietti and Giovine 2008). Photo by Guido Motofico, courtesy of the Natural History Museum of Ireland.
OUR WOODEN FISHING BOAT, Patuno, creaks and sways as we motor from the 500-year-old port of Wanci, tucked in the Wakatobi Islands of Indonesia. This marine national park is in the Coral Triangle, at the center of ocean biodiversity, rich in high numbers of species, from corals to fish, and home to many Blaschka lookalikes. Patuno, with her handcrafted wooden hull, twentyfoot-wide deck, and truncated stern, is like many of the remaining Indonesian Phinisi boats, designed in the 1500s with mast and sail and retrofitted more recently for motorized travel. We are headed for the reefs adjacent to the tiny island of Kapota, hoping to find a thriving diversity not just of sea slugs, but also of octopuses, squid, and cuttlefish—all of which were abundant here during the Blaschkas’ era.
It’s easy to see why sea slugs are a group the Blaschkas singled out. Consider their unusual mix of colors, from bright reds and canary yellows to soft lavenders, leafy greens, and the biologically rare chrome blues. With their elaborate patterns of stripes, spots, and deadly feathered armor, these predatory dragons light up the deep despite their diminutive size. The smallest among them is no bigger than a ladybug. The Blaschkas captured every tiny detail. Of the 569 Blaschka sea animals in Cornell’s collection, approximately 94 are models of these charismatic little creatures, known as nudibranchs. As Prometheus stole fire from Zeus, so these animals steal the stinging harpoons from their prey—anemones and jellyfish—and zip them into their own backs as co-opted weapons of defense. But unlike Prometheus, evolution has diversified our nudibranchs and they are favored through eternity for the theft. They thrive in the cool waters of the Mediterranean and British Isles and are most diverse in the warmer oceans of the world, including here in Southeast Asia, where I am looking for the more unusual tropical ones. There are over 700 species populating the Coral Triangle, and I’m hoping to find lots of living counterparts to the Blaschkas’ beautifully crafted replicas, but I am only cautiously optimistic. Like many ecosystems around the world, Indonesia’s once-rich marine habitats have been bedeviled by human impacts. Degraded by over-fishing and over-use, still-living reefs are littered with lost fishing gear, including lines, nets, and trash bags. Beyond that, vast stretches of standing corals, overcome by coastal pollution and too-warm oceans, lie dead and bleached, the weathered bones of a once vital ecosystem. The rich spectacle of colorful sea creatures that once depended on this environment is likewise absent, relegated to pockets of still-healthy reefs in the more remote waters of Indonesia’s less populated islands, or in protected national parks like Wakatobi’s marine preserve.
Of all the problems plaguing Indonesia, however, blast fishing with bombs is the most immediately destructive. Not only do nitrogen-fertilizer bombs destroy the very framework of the reef by blowing it to smithereens, but they also remove the richest ocean habitat on our planet in the actions of a single night. It’s worrisome to me that the level of destruction from blast fishing only seems to grow with each new visit I make to Indonesia, while the public and many conservation managers on the outside think it has been reduced, since it is technically illegal. The only upside is that it’s also the most potentially fixable threat to marine life, since Indonesia has already legislated it as an illegal practice and, with enough resources and social programs, surveillance and protection could curtail it. This seems a far easier fix than expecting all the nations of the world to immediately adopt a carbon-reduction treaty to reduce ocean warming and acidification. My hope is that the data we gather here will help with biodiversity conservation and the development of new approaches to sustaining the lifeblood of biodiversity. But it’s difficult not to be moved by the terrible destruction in this rare and beautiful place. The rate and range of destruction cannot be overstated. I was about to see firsthand a region of coral change from pristine to devastated in the length of a football field.
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Wakatobi is in the heart of the Coral Triangle, where the biodiversity of all molluscs is high compared to the Caribbean. There are approximately 6,000 species of nudibranchs worldwide, in a dazzling diversity of colors and shapes, and approximately 151 are described in the Caribbean (Garcia and Bertsch 2009). The biodiversity of the nudibranchs in some areas of the Coral Triangle is estimated to tip the scales at over 700 species (see www.seaslugforum.net) and includes bright spotted slugs like the one depicted by the Blaschkas (page 88). Wakatobi sits east of the great Wallace Line of terrestrial faunal divide, drawn in 1859 by the British naturalist Alfred Russel Wallace, that separates the ecozones of Asia and Australia. The Wallace Line was drawn with terrestrial vertebrates in mind—think panda bears to the west and kangaroos and koalas to the east—and it’s only recently that scientists have been able to verify similar divisions within marine species. Faunal boundaries can be zones of unusual diversity, since the animals and plants on both sides can creep across. I like to think of this area as the Glass Triangle, due to the fragility of its marine biodiversity in this modern world.
I had dived Indonesia’s Wakatobi Islands three years previously and remembered it as a beautiful area, abundant with sea life. During that trip, I’d visited the Waha Wall, which we planned to revisit on our way to Kapota Island. As a Coral Reef Rehabilitation and Management (COREMAP) site, it is part of a series of over 400 small protected areas funded through the World Bank. The goal of the project is to improve stewardship of vital marine resources, like coral reefs, which are so valuable to the local economy through fisheries and tourism. When I’d last visited, the coral wall, which extends hundreds of feet into the o
cean depths, was healthy and filled with bright fish and colorful coral. This time, however, we took a wrong turn and headed south toward town rather than north to the COREMAP reserve site. I hadn’t previously seen how small the oasis of the preserve really was. As we donned our masks and surveyed the site, close to houses on shore, there was no clue to the impacts we were about to see. Once underwater, we immediately noticed scattered stands of dead coral along the top of the wall, and a lack of bright fish. We dropped over the reef edge and encountered a monstrous old fishing net, ominous and algae fouled, wrapped around the once-living coral and stretching forty feet across the reef, suffocating whole sections. More intangible, unseen killers, like coastal pollution, had killed whole colonies of coral, leaving only the dead white skeletons as a ghostly calling card. Our job changed from one of seeing the rare and beautiful creatures the Blaschkas had idealized in glass to one of cataloguing things killing the reef. It was uninhabitable to the creatures we sought and we came up empty, seeing no nudibranchs, octopuses, or cuttlefish.
These reefs and the biodiversity they house are not just a vital source of livelihood for the coastal residents, they are also world treasures, cathedrals to living biodiversity. Leopold Blaschka could never have imagined the devastation we would wreak on the habitats of his beloved sea slugs. I was disheartened by the evidence of our disregard for nature. I hoped that when we ultimately reached Kapota, we would find a more promising environment.
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Nudibranchs are part of a larger group of snails without shells that we affectionately call sea slugs. Put simply, sea slugs include sea butterflies, sea elephants, sacoglossans, and nudibranchs, and the Blaschkas captured them all in watercolor and glass. Nudibranchs are named after the Latin term for “naked gills” because they have no shell in the adult phase and their gills are often exposed as great colorful plumes on their backs (page 105). As a group, they are divided into different families characterized by specific body forms and prey types. For example, the aeolids have bright plumes on their backs; this is the group that can transfer weaponry from their prey, anemones, to their back plumes (page 95). Members of the dorid family, which includes the bright chromodorids we will see on our dive, are somewhat flattened and have a distinctive ring of retractable gills on their backs; they mostly feed on sponges and the lesser known bryozoans. Finally, the dendronotid family is a smaller group of often large nudibranchs with elaborate plumes and branched back sculpture. Most of the Blaschka glass nudibranchs are uncannily exact matches to the living ones. In photographs, it’s almost impossible to distinguish glass from living.
The variable neon slug (Nembrotha kubaryana) in Indonesia’s Wakatobi Islands, where it feeds on sea squirts. This specimen was an exact match for the Blaschkas’ glass model. Photo by David O. Brown.
I started my career as a biologist by studying the predatory behavior of nudibranchs in the San Juan Islands of the Salish Sea, so I can well understand the passion the Blaschkas had for this group of ferocious sea slugs. As I tramped through tide pools, turned over rocks, looked under docks, and dove in the cold water of the Salish Sea, which teems with over eighty-six species of nudibranchs, I became captivated by their spectacular beauty and unusual biology. I think the Blaschkas, like me, were mesmerized by the exquisite watercolors of Joshua Alder and Albany Hancock, naturalists who described every possible species of British nudibranch in their taxonomic treatise of 1840. Their inspiring watercolor monograph is partly the reason the Blaschkas were so enamored of nudibranchs. For example, if you compare the Blaschka watercolor and the earlier Alder and Hancock watercolor of Dendronotus, the origins of the Blaschka illustration are clear (page 96). Or the brilliant red Facelina (above) and the red-spotted Doto, which my student, Reyn, documented in 2013 on Appledore Island in Maine (page 97). Both of these species were common 160 years ago in Britain, when Alder and Hancock were at work, and they were common in 2013 when I taught my marine biodiversity course at Shoals Marine Lab on Appledore Island in Maine. Even Ernst Haeckel, one of the most famous biologists of the nineteenth century, was mesmerized by the forms and colors of the nudibranchs, and we know that his watercolors had a big influence on the Blaschkas’ artistry.
Facelina bostoniensis, a nudibranch from the aeolid family, in glass (top) and alive at Shoals Marine Lab in New Hampshire. Photos by Kent Loeffler (top) and Drew Harvell.
What were the Blaschkas thinking about the life of each species as they sketched, painted, and crafted them in glass? We know from their sketchbooks that they were careful scholars when it came to external anatomy and understanding how it was linked to internal anatomy. It’s unclear, however, whether they knew enough about natural history to recognize that nudibranchs are voracious predators and actively hunt anemones and sponges, or that they are exceptionally choosy. Biologists would call them trophic, or food specialists, because each nudibranch species often only eats a single species of anemone. Surely the Blaschkas knew that the nudibranch Aeolidia papillosa, still common today on both Atlantic and Pacific shores, was a deadly force, stalking the plentiful plumose (Metridium senile) and elegant anemones (Anthopleura elegantissima). I imagine they must have perched beside tide pools and watched the cream- and ivory-colored sea slug creep up on its anemone and then pounce on the column, rasping at its tissue with a highly specialized, sharp-toothed radula. The radula is the ribbon of teeth that is a distinctive feature of all molluscs, and the shape and size of the teeth change with each prey type. This is a tightly coevolved predator-prey interaction that has been playing out in tide pools for millions of years. Or consider the tiny nudibranch species Doridella steinbergae, perfectly matched in white color and boxy pattern to the single species of bryozoan that it eats, Membranipora membranacea. The life cycles of predator and prey are so intertwined that the larval stage of the nudibranch will only metamorphose from its planktonic form to begin bottom life when it finds this one species of bryozoan.
The frond aeolis (Dendronotus frondosus) in a watercolor (top) and alive. From Joshua Alder and Albany Hancock, Monograph of the British Nudibranchiate Mollusca, 1845–1910. Watercolor courtesy of the Albert R. Mann Library, Cornell University. Photo by Drew Harvell.
The crowned doto (Doto coronata) in glass (left) and alive at Shoals Marine Lab. Photos by Claire Smith (left) and Reyn Yoshioka.
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I like to think that the Blaschkas were just as intrigued by the fierce machinations of these tiny creatures as I am. What would our own team find as we prepared to enter the rich waters off Kapota Island?
Our captain edges Patuno close to the reef top adjacent to Kapota Island, hovering over the edge of a coral cliff that drops from three feet to hundreds, with no bottom in sight. Once underwater, I am immediately struck by the wealth of life that’s teeming here, unlike at Waha Wall. No trash or nets or broken coral. Instead, I am greeted by towering walls of reef coral festooned with sponges, soft corals, and crinoids. I am relieved to find clear water and bright biodiversity as we begin our search for the wily nudibranchs. I hope for a high diversity of nudibranchs, but some are as small as a caterpillar and hard to find. Lucky for us, my Indonesian diving guide, Jardeen, is a talented nudibranch hunter. Like many Indonesians in this remote place, he speaks only Bahasa and understands a smattering of English. So our relationship is built on gestures and actions, which is all one needs underwater. David is here, too, camera in hand, hoping to capture some animals on film as I try to catalogue them. The water is sharply clear, and the bottom is alive with 80 percent coral cover and hundreds of different species. We pause transfixed by fish in every color, size, and shape zipping around like small rockets. There are wrasses and clownfish and angelfish and butterflyfish. Within seconds, it’s easy to see there must be at least fifty species of fish. It’s a carnival of sea life, filled with an exotic and breathtaking mix of creatures. Striped sea snakes undulate across the reef; green turtles zoom by, unimpressed by our presence; giant clams gape open to reveal fluorescent blue-spotted gil
l covers; yellow and bright pink crinoids perch high on coral outcrops (page 140).
We go deeper. Once we’re along the cliff at forty feet below the surface, the current picks up. As we start to drift ever faster along the wall, we watch the pattern of Indo-Pacific biodiversity flash before us. David struggles to capture on film the multitude of brilliant sponges, bright corals in a rainbow of colors, multicolored crinoids unfurling their arms in the current, and a myriad of coral reef fish. There are sharks around, but we are so focused inward toward the reef they could be dancing behind us and we’d never see them. But where are the nudibranchs? Surely, in this diverse ecosystem, we’ll find one. Suddenly, I hear a metal clanging underwater and know that Jardeen has found something exciting and is banging signals on his tank. Sure enough, there it is, a vivid flash of blue and orange nestled on the vertical wall of sponge, a rather tiny chromodorid nudibranch, much smaller than a caterpillar. It has a bright blue body with even brighter orange tentacles, called rhinophores, and bright orange matching gills (page 105). This relatively common chromodorid, Chromodoris annae, feeds only on one group of chemically noxious sponges and absorbs as its defense the active chemicals from these sponges that are distasteful to fish (see the Sea Slug Forum, www.seaslugforum.net).