A Sea of Glass Page 5
My students and I, ever fascinated by different habitats and invertebrate forms, had often joked that while “the black water dive” in Hawaii was a very exciting opportunity to see unusual bioluminescent plankton, it was too scary to actually do. For those of us used to working on shallow reefs in bright day, it was not appealing to imagine being set like a fishing lure in the middle of the darkened Pacific Ocean, where you’re at risk of encountering great white and tiger sharks during their prime feeding hours. Of the 480 shark species, only great whites, tigers, and bulls are responsible for double-digit attacks on humans, and both great whites and tigers are still common in the waters off Hawaii. Of course the danger to us is vanishingly small; some estimates put the probability of being attacked by a shark at one in a million, but low probability events can loom large in the dark, especially in a year that had seen a record fourteen shark attacks and two deaths in the Hawaiian Islands. On our black water dive, we would be clipped with carabiners to weighted fifty-foot lines from the boat; we would be able to swim up and down the lines but would not be in danger of dropping too deep or getting left behind if a strong wind pushed the boat too fast.
Geared up in the dark rocking boat, David, Catherine, and I clipped onto our safety lines, talking about what we hoped to see on this dive. As always, David hoped to see his favorite invertebrate, which is any kind of octopus or squid. A night dive in the open ocean is the realm of oceanic squid and planktonic baby octopuses, some no bigger than your thumbnail. Catherine didn’t say, but I knew she was the one hoping to see sharks in the dark. My thoughts were on the bioluminescent siphonophores we might see and my hope there would not be minefields of stinging tentacles. Still talking, we slipped below the surface without lights, into darkness punctuated by bioluminescent splashes.
The bioluminescence of jellyfish is also what first inspired Leopold Blaschka to craft sea animals from glass. Although his first models, inspired by the anemone watercolors of Gosse, were of anemones, in 1864 he began experimenting with jellyfish and squid in glass (Reiling 1998). Seeking solace after the death of his wife, he traveled aboard the brig Pauline to North America in 1853. The boat was becalmed on the Atlantic, and this is where Leopold observed several species of jellyfish, including the Portuguese man-of-war. His diary entry from this voyage reveals how entranced he was by the forms of the jellyfish and their evening light shows of bioluminescence. This is the moment, on one of those still ocean evenings, when he first sees the live, bioluminescent jellyfish appearing as if spun from glass:
We are on a sailing ship in the Atlantic Ocean, immobilised because of the calm; it is a beautiful night in May. Hopefully we look over the darkness of the sea which is as smooth as a mirror: in various places there emerges all around a flash-like bundle of light beams, like thousands of sparks, that form true bundles of fire and of other bright lighting spots, as if they are surrounded by mirrored stars. There emerges close before us a small spot in a sharp-greenish light, which becomes ever larger and larger and finally forms a bright shining sun-like figure. A second one develops, a third; ten, a hundred of these suns light up at a certain distance from the peculiarly sparkling intervals, bright lighting circles form strangely formed figures, with in between places in a glowing light, an indescribably beautiful scene originates . . . it is, as if they wanted to lure the enchanted observer into a realm of fairies. (Reiling 1998)
In our open-ocean realm of fairies, those bioluminescent splashes started to come by fast, but we had to drift close to identify whether they were jellyfish, ctenophores, salps, squid, or pelagic snails. Collectively, these pelagic open-ocean animals make up over a hundred of our glass models.
As we settled into our depth and turned on lights, we could see a glittering stream of tiny plankton float by us. It was an eerie and unnerving experience to hang in the dark ocean, straining to see what might be coming next, completely unable to see what was below but knowing the bottom stretched hundreds upon hundreds of feet down and was full of big things that might eat us. Would great white sharks or enormous Humboldt squid come shooting from the depths? I nervously double-checked my tether, since it was my only link to the line that allowed me to know up from down. With no lighted surface for orientation, no ability to see my bubbles, and almost weightless, I could not orient myself in space. Then, at the edge of my light, I saw a whiter, glowing shape and pulled to the end of my tether to get a look. A baseball-sized lobate ctenophore, propelled with a changing rainbow of reflective purple, gold, and blue cilia, swam through the beam. These large lobate ctenophores are predators closely resembling the swimming bells of the cnidarian jellyfish. They are also called comb jellies because of the way their sparkling cilia are arranged in orderly rows, like the teeth of a comb. In a bizarre reversal of the normal case where fish eat jellies, these large lobate ctenophores are capable of gobbling small fish from the water column, and in large numbers they can impact the food web. In one instance in the 1980s, an invading species of ctenophore, Mnemiopsis leidyi, cleared the Black Sea of fish. Why? Partly because it was a new invader, but also because it entered an over-fished sea that lacked top predators like mackerel and offered nutrient-rich conditions that were optimal for Mnemiopsis.
The lobate ctenophores are not a Blaschka match, but as this pulsing, glassy predator moves off, in glides one of its strange cousins, the Venus girdle ctenophore, Cestum veneris. It is otherworldly, a transparent, foot-wide, ribbon-thin wing swimming through the water, hunting for small zooplankton. I can see this thin transparent animal only because of the light of the flickering iridescent ridges of its comb rows as it swims steadily past. This ctenophore is only a foot wide, and the Blaschkas’ work in glass is even smaller, but the Mediterranean one can be over three feet wide. Not only does it look mysterious, but as far as I know, its role in nature is poorly understood. As this unusual Blaschka match swims off, I have time to catch my breath and look around, remembering to wonder about sharks. Happily, none have appeared.
I also did not want to blunder into either a Portuguese manofwar siphonophore or an even more venomous cubomedusa, like the Irukandji, in the dark Hawaiian waters. Sure enough, the siphonophores were putting on a breathtaking show. Small, fast, and bioluminescent, they were tiny flashes of jet propulsion. When hunting, they stretch out their long tentacles to five times their contracted lengths of four inches or so. When prey is captured, they haul in their lines. And when danger bumps, giant axons fire a signal to contractile muscles that zip up the tentacles, and the bell powers into high speed; what was a foot-long string of stinging tentacles disappears in a four-inch flash of jet propulsion. Somehow the name “jellyfish” doesn’t quite capture the extravagant evolution and biology at work here.
It was surreal and sublime to drift motionless in the middle of the Pacific Ocean, fifty feet down, watching a parade of diversity wash past us. We could feel and see the pulse of the ancient food web of the ocean, which seemed unchanged from deep time of 500 million years ago. Like the bioluminescence that first captivated Leopold Blaschka, with our lights off, we could see first a flash and then whole chains of light drifting through the water, emitted by the siphonophores and ctenophores. We continued to enjoy the light show as we slowly ascended our lines to return to the waiting boat and hot tea.
But just how “unchanged” are these food webs, let alone the oceans they inhabit? I was determined to find out by going to the habitats that first inspired the Blaschkas.
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The Ligurian coast of Italy should be ground zero for finding the most Blaschka matches, because the Blaschkas had many live animals sent to them from the marine lab Stazione Zoologica Anton Dohrn in Naples. I was on the lookout not only for jellyfish but also for octopuses and small, bright nudibranchs. On my first scoping trip as part of a family vacation, I was able to do two dives on the Ligurian coast. My scientific colleague Dr. Sylvia Cocito from the Centro Ricerche Ambiente Marino di Santa Teresa dell’ENEA in La Spezia had sent me to this rocky outcrop of land
called Portofino, right at the top of the Italian boot. She suggested this as the spot with the highest marine biodiversity in the Ligurian Sea. Sylvia reported that many habitats in the Ligurian Sea had been over-fished and were severely depleted, but that Portofino was a rare oasis of biodiversity and might be a refuge for some Blaschka invertebrates. I needed to see for myself how these creatures were faring.
My target was to dive inside the no-fishing preserve on the rocky headland of Portofino. We had waited over ten days, hiking the trails of the Cinque Terre, for the extremely high winds, rough waves, and rain to pass. It finally dawned bright, the seas flat calm, and my son Nathan and I decided to give it a try. Nathan, a college senior, had trained to dive in the warmer waters of Hawaii and was adept at finding rare fish and invertebrates.
We arrived at our first dive site, a shipwreck outside the preserve that was exposed to the full fetch of the Mediterranean, whose waves were crashing high plumes of spray against the sheer rock walls. We were outfitted in unfamiliar cold-water dive gear and accompanied by a divemaster who spoke only Italian, which we did not. Fortunately, many aspects of launching, conducting, and returning from a dive are prescribed by safety rules that are universal, so we understood most of the plan: drop over the side, wait at the surface buoy for the group to assemble, find your buddy, and drop slowly along the safety line to the bottom, sixty feet down.
Once safely at depth, where it was nearly dark, interesting animals loomed along the wall beside the submarine-sized, somewhat ominous wreck of the old cargo ship Mohawk Deer, which sank in 1967 as it was returning to port. As we swam cautiously around the hull, uncertain of what might come zooming out of the depths, we admired a brilliant covering of orange tentacles attached to an endemic and endangered cup coral and a Blaschka match, Astroides calycularis (page 34). After rounding the spooky wreck, we moved along a sheer wall and found, tucked into a crevice, a mouse-size tube anemone with long red and black tentacles (Cerianthus membranaceaus). It was similar to our Blaschka tube anemone and was the largest and brightest tube-building anemone I had ever seen. Nathan and I communicated our excitement at what we were seeing through a series of squeaks, hmmunhs, and hand signals. We worked our way around the wreck, finding, spotlighting, and photographing a whole series of Blaschka matches: orange Astroides cup coral; golden star coral (Balanophyllia regia); orange sea squirt; several feather worms, including the Mediterranean feather duster; and two colonial ascidians. Always a pro at finding the right critters, Nathan eventually gestured me over to see the living counterpart of one of my favorite Blaschka watercolors, the red-tentacled tube-building worm Serpula vermicularis (page 84). I hovered there, feeling the thread of time between Leopold Blaschka and me spooling back on itself as I watched this small worm feeding in the current, much like its ancestors had when Blaschka first captured them in glass.
After we circled the wreck and the wall, the divemaster gestured us toward shallower water and moved off quickly. Before I knew it, we were on an unplanned ascent to shallow water and suddenly entered the realm of the mauve stinger jelly, which I didn’t then realize was dangerous. After I finished admiring the amethyst-studded purple bells and eighteen-inch-trailing mouth palps (page 55), I noticed the almost invisible, translucent tentacles trailing twenty feet beyond the jellyfish. They were set like a minefield stretching from the bell of the jellyfish to the tips of its tentacles. While I didn’t know its reputation as a hazard, it did occur to me that they would be loaded with stinging nematocysts that could deliver a neurotoxin as potent as that of the Portuguese man-of-war. No worry, even though we were in the middle of a swarm of over thirty jellies. The water was cold, about 63°F, and I was buttoned up in neoprene so tight, from thick hood to dry suit, that I was completely impervious to tiny harpoons from even the most toxic jellyfish. What I didn’t know was that similar swarms of this jelly had just cleared the beaches of the Mediterranean from Catalonia to La Spezia. Its toxin-loaded tentacles had been responsible for tens of thousands of emergency room visits and even a fatality. It is also one of the more spectacular of the glass models in our Blaschka collection and one that never fails to bring me straight to the feeling of being in the open ocean. While it was awe inspiring to be in the midst of these otherworldly creatures, the sheer size of this jellyfish bloom indicated that the ecological conditions here were out of balance.
The mauve stinger is a predatory jellyfish that snags small larval fish with long invisible tentacles, stunning them with harpoons of stinging cells, then retracts the meal to its mouth palps. But it isn’t the abundant food that is spurring these jellyfish blooms; instead, it’s what ecologists call the “top-down effect.” Put simply, the predators that once controlled jellyfish populations are missing from much of the Mediterranean, including our first dive site. Not a fish could be seen and certainly not the turtles and sunfish that normally eat the adult mauve stinger. And Pelagia wasn’t the only Blaschka-match jellyfish that was present in bloom conditions during our dives. Some of the beaches had taken on a blue sheen from the rafts of small, cobalt-blue by-the-wind sailors (Velella velella) that had washed ashore (page 57). Although the animal is no bigger than a bar of soap, the blooms were so big that the entire surface of the bay glistened from the reflections of their transparent sail-like fins. Velella is called by-the-wind sailor because it has a stiff, functional, transparent sail that catches the wind and propels the jellyfish through the water. Beneath the sail and the float that keeps it at the surface is the business part of the jelly—a bright blue collection of stinging tentacles that stretch down to ply the waters for baby fish. Look more closely at the mass of bright-blue tentacles and you will find that this is actually a colony with hundreds of polyps, some specialized for feeding, some loaded with stinging cells for defense, and others for reproduction. The reproductive polyps release hundreds of tiny medusae, each of which will sail the sea for three weeks under solar power provided by their symbiotic algae. These halfinch voyagers will mature and release eggs and sperm, which will in turn develop into a new sailor. How incredible is this adaptation of a jellyfish for voyaging the seas? Even better: some forms are right-handed and are driven by the winds in a clockwise gyre, and on others, the sail is set crosswise and travels the opposite route.
The mauve stinger (Pelagia noctiluca), a jellyfish with a sting capable of clearing Mediterranean beaches. (From left) a live jellyfish in the Mediterranean, a Blaschka jellyfish in glass, and a Blaschka watercolor. Photos by Drew Harvell (left) and the Muséum d’Histoire Naturelle, Geneva. Watercolor courtesy of the Rakow Research Library, Corning Museum of Glass, BIB ID: 122405.
By-the-wind sailor (Velella velella) in glass (left) and washed onto a Mediterranean beach, where it can gather into huge blue-tinted windrows. Photos by Claire Smith (left) and Drew Harvell.
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While some of the Blaschkas’ fascination with jellyfish originated with Leopold’s first open-ocean experiences and the animals’ glass-like appearance, another influence played prominently in the jellyfish theme. Ernst Haeckel (1834–1919), a professor at Jena University, was both a scientific giant of his time and a highly controversial figure. He described more than 2,000 genus names and more than 3,500 new species of invertebrates (Reiling 1998). Haeckel’s chief scientific interests lay in evolution and life development processes in general, which culminated in his beautifully illustrated Kunstformen der Natur (Art Forms of Nature), a collection of one hundred detailed color illustrations of animals and sea creatures.
Haeckel is notorious for his biogenic law, commonly referred to as the “theory of recapitulation.” Haeckel’s recapitulation theory posits that the embryonic development of the individual of every species (ontogeny) fully repeats the historical development of the species (phylogeny). In other words, each successive stage in the development of an individual represents one of the adult forms that appeared in its evolutionary history. He posited that a group of related animal forms could be viewed as steps in an evolutionary seri
es, and that by studying a succession of shapes in embryonic development, the laws that define the form of the adult organism could be clarified. For example, Haeckel proposed that the pharyngeal grooves in the neck of a human embryo not only resembled the gill slits of fish, but also signified the trace of a fishlike ancestor. When fossil records were not available, the study of embryonic stages could show scientists what the animal’s ancestors looked like. Although the ideas were appealing and captured important biological insights, some of the details have also been discredited (Gould 2000).
We know from the letters that both Leopold and Rudolf wrote to Haeckel that the Blaschkas admired and followed Haeckel’s work closely, and we can see the evidence of it in their work (Reiling 1998). This influence appeared first in some of the Blaschkas’ watercolors of anemones, which copied the exact forms of watercolors by both Haeckel and Philip Henry Gosse. Henri Reiling emphasizes that the admiration was mutual and the passion was shared; Haeckel included a photograph of a Blaschka glass model, Bougainvillia fruticosa, in his book Die Natur als Künstlerin (Nature as an artist, 1913).
Dresden, 11 June 1877
Highly esteemed Mr Professor,
After I diligently copied and studied all that was necessary from the books by Agassiz and Milne Edwards, that you kindly lent me,
I return these to you at the same time by mail and again I most kindly thank you for all your obliging complaisance. It enabled me indeed to execute my new catalogue more completely and only limited to scientific models.
Again most kindly thanking,
greeting,
with all respect
yours devoted
L. Blaschka
Rudolf displays the same respectful, eager charm in his continuing correspondence with Haeckel a few years later (Reiling 2007):