October 15, 2013
The sea has been the stage for monstrosities and strange tales since antiquity. And, why not? Unlike land, the ocean is constantly shifting and moving, with currents that could carry a ship off course and storms that threaten wrecks. Even the substance itself, seawater, is often cold and dark, and deadly to drink in quantity. So, what of the creatures that were thought to live there?
The sea monsters that populated European medieval and renaissance imaginations—fierce-toothed animals battling in the waves, long serpents wrapped around ships, torturously beautiful sirens and a wide assortment of chimeric beings—are the subject of two new books. Sea Monsters on Medieval and Renaissance Maps, by Chet Van Duzer, and Sea Monsters: A Voyage around the World’s Most Beguiling Map,by Joseph Nigg, both focus exclusively on illustrations, several of which are included here, of such monsters on old maps.
More than mere marginalia and playful illustration, cartographers drew sea monsters to enchant viewers while educating them about what could be found in the sea. Most of the decorated maps weren’t used for navigation, but rather were displayed by wealthy people. That doesn’t mean the monsters were purely ornamental inventions though. “To our eyes, almost all of the sea monsters on all of these maps seem quite whimsical, but in fact, a lot of them were taken from what the cartographers viewed as scientific, authoritative books,” said author Chet Van Duzer in a podcast with Lapham’s Quarterly. “So most of the sea monsters reflect an effort on the part of the cartographer to be accurate in the depiction of what lived in the sea.”
There was a long-held theory, going back to at least the first century with Pliny the Elder’s Natural History, that every land animal has an equivalent in the ocean. There were thought to be sea dogs, sea lions, sea pigs—you name it. Some of these are now the names of real animals—sea lions are eared seals and sea pigs are deep-water sea cucumbers (tube-like relatives of sea stars) with legs. But the medieval imaginings were the literal hybrid of fish with the known land animal.
Some of the illustrations, however, are closer to real animals but warped into monstrous forms. Whales were typically drawn with beastly heads, like a cross between a wolf and a bird, with tusks or large teeth and waterspouts. Despite their generally gentle nature, they were often drawn attacking ships. While it’s unlikely that such confrontations were frequent, it’s easy to imagine the fear welling up when a sailor spotted the back of a whale longer than his ship rise above the waves. If it jumps from the water, is it on the attack?
These uneducated sailors were the main sources for artists and writers trying to describe life in the ocean. So, their reports of monsters—from the singing sirens that lure sailors to jump to their deaths to the the lobster-like “octopuses” and various serpents and worms—became the basis of natural history texts and drawings on maps. These maps then helped perpetuate the life of these creatures, as they inspired travelers on the dangerous sea to confirm their existence.
However, at the end of the 17th century, sea monsters start to disappear from maps. European understanding of science was growing, and the printing press made the spread of realistic images easier. “As technology advanced, as our understanding of the oceans and navigation advanced, more emphasis was placed on human’s ability to master the watery element: to sail on it and conduct trade on it,” Van Duzer told Lapham’s. “And thus images of the dangers of the sea, while they certainly did not immediately disappear from maps in the 17th century, became less frequent over time, and images of ships became more common.”
There were still illustrations on maps, but they were far more pragmatic. Ships indicated areas of safe passage, while drawings of fish and whales showed good fishing areas. On one map from the early 17th century, vignettes illustrated how to kill and process a whale. “Whales, the largest creatures in the ocean, are no longer monsters but rather natural marine storehouses of commodities to be harvested,” wrote Van Duzer. Some of the mystery is gone as the sea becomes another resource rather than a churning darkness to be feared.
Just when you think that we’ve lost that sense of awe at the sea, captured in these old maps and texts, we are reminded that much remains to be discovered in the ocean. This year, both the giant squid and the 15-foot megamouth shark were filmed for the first time, and there is still plenty to learn about each. We’re still dazzled by bioluminescent light displays in the deep, or the surreal, shimmering movements of schools of millions of tiny fish. The awe continues—it’s just based on fact rather than fantasy.
Learn more about the ocean at the Smithsonian’s Ocean Portal.
September 16, 2013
Ocean acidification has taken up an unlikely mascot: the shelled pteropod. While “charismatic megafauna,” the large creatures that pull at our heartstrings, are typically the face of environmental problems—think polar bears on a shrinking iceberg and oil-slicked pelicans—these tiny sea snails couldn’t be more different. They don’t have visible eyes or anything resembling a face, diminishing their cute factor. They can barely be seen with the human eye, rarely reaching one centimeter in length. And the changes acidification has on them are even harder to see: the slow disintegration of their calcium carbonate shells.
Even without the threat of more acidic seas—caused by carbon dioxide dissolving into seawater—pteropods (also called sea butterflies) look fragile, as if their translucent shells could barely hold up against the rough ocean. This fragility is what attracted artist Cornelia Kavanagh to sculpt the miniscule animals. Her series, called “Fragile Beauty: The Art & Science of Sea Butterflies,” will be on display at the Smithsonian National Museum of Natural History’s Sant Ocean Hall starting September 17.
“By making visible that which is essentially invisible, my pteropod sculptures could dramatize the threat of ocean acidification in a refreshing new way, causing the pteropod to become a surrogate for a problem of far-reaching implications,” says Kavanagh.
Ocean acidification is expected to affect a panoply of ocean organisms, but shelled animals like corals, clams and pteropods may be hardest hit. This is because the animals have more trouble crafting the molecular building blocks they use to construct their shells in more acidic water.
Pteropods and other shelled animals that live near the poles have an even bigger challenge: they live in cold water, which is historically more acidic than warm water. Acidification is expected to hit animals in colder regions first and harder—and it already has. Just last year, scientists described pteropod shells dissolving in the Southern Ocean off the coast of Antarctica. These animals aren’t just struggling to build their shells; the more acidic water is breaking their shells apart.
While Kavanagh’s sculptures were made before this discovery, she still tried to portray the future effects of acidification by sculpting several species of pteropod in various stages of decay. Some of her pteropods are healthy, with whole shells and “wings”—actually the snail’s foot adapted to flap in the water—outspread. Others have holes in their shells with folded wings, so the viewer can almost see them sinking to the seafloor, defeated.
Before starting this project, Kavanagh had never heard of pteropods. She wanted to make art reflecting the impacts of climate change, and was searching for an animal with an appealing shape for abstraction. One day she stumbled upon the image of a pteropod and was sold. She found the animals both beautiful and evocative of the work of Modernist artists she admires, such as Miro, Arp and Kandinsky.
She based her aluminum and bronze sculptures off of pictures she found in books and on the internet, blown up more than 400 times their real size. But when she finished sculpting, she panicked. “While I tried to symbolize the danger pteropods faced by interpreting their forms,” Kavanagh says, “I became increasingly concerned that my sculptures might be too abstract to be recognizable.”
She contacted Gareth Lawson, a biological oceanographer at Woods Hole Oceanographic Institution, who studies the impacts of acidification on pteropods. To her relief, when he looked at pictures of her sculptures, he was able to easily identify each down to the species. After that, the pair teamed up, writing a book together and curating a show in New York, called “Charismatic Microfauna,” with scientific information alongside the sculptures.
“What drew me to [Cornelia's] work in particular is the way in which, through their posture and form, as a series her sculptures illustrate pteropods increasingly affected by ocean acidification,” says Lawson. “Through her medium she is ‘hypothesizing’ how these animals will respond to the changed chemistry of the future ocean. And that’s exactly what my collaborators and I do, albeit through science.”
May 14, 2013
The chemistry of the ocean is changing. Most climate change discussion focuses on the warmth of the air, but around one-quarter of the carbon dioxide we release into the atmosphere dissolves into the ocean. Dissolved carbon dioxide makes seawater more acidic—a process called ocean acidification—and its effects have already been observed: the shells of sea butterflies, also known as pteropods, have begun dissolving in the Antarctic.
Tiny sea butterflies are related to snails, but use their muscular foot to swim in the water instead of creep along a surface. Many species have thin, hard shells made of calcium carbonate that are especially sensitive to changes in the ocean’s acidity. Their sensitivity and cosmopolitan nature make them an alluring study group for scientists who want to better understand how acidification will affect ocean organisms. But some pteropod species are proving to do just fine in more acidic water, while others have shells that dissolve quickly. So why do some species perish while others thrive?
It’s a hard question to answer when scientists can hardly tell pteropod species apart in the first place. The cone-shaped pteropod shown here is in a group of shelled sea butterflies called thecosomes, from the Greek for “encased body.” There are two other groups: the pseudothecosomes have gelatinous shells, and the gymnosomes (“naked body”) have none at all. Within these groups it can be hard to tell who’s who, especially when relying on looks alone. Scientists at the Smithsonian’s National Museum of Natural History are using genetics to uncover the differences among the species.
This effort is led by zoologist Karen Osborn, who has a real knack for photography: in college, she struggled over whether to major in art or science. After collecting living animals while SCUBA diving in the open ocean, she brings them back to the research ship and photographs each in a shallow tank of clear water with a Canon 5D camera with a 65mm lens, using three to four flashes to capture the colors of the mostly-transparent critters. The photographs have scientific use—to capture never-before-recorded images of the living animals—and to “inspire interest in these weird, wild animals,” she said. All of these photos were taken in the Pacific Ocean off the coasts of Mexico and California.
Although sea butterflies in the gymnosome group, like the one seen above, don’t have shells and are therefore not susceptible to the dangers of ocean acidification, their entire diet consists of shelled pteropods. If atmospheric CO2 continues to rise due to the burning of fossil fuels and, in turn, the ocean becomes more acidic, their prey source may disappear—indirectly endangering these stunning predators and all the fish, squid and other animals that feed on the gymnosomes.
For years, sea butterflies were only collected by net. When collected this way, the animals (such as Cavolinia uncinata above) retract their fleshy “wings” and bodies into pencil eraser-sized shells, which often break in the process. Researchers then drop the collected pteropods into small jars of alcohol for preservation, which causes the soft parts to shrivel—leaving behind just the shell. Scientists try to sort the sea butterflies into species by comparing the shells alone, but without being able to see the whole animals, they may miss the full diversity of pteropods.
More recently, scientists such as Osborn and Smithsonian researcher Stephanie Bush have begun collecting specimens by hand while SCUBA diving in the open sea. This blue-water diving allows her to collect and photograph fragile organisms. As she and her colleagues observe living organisms in more detail, they are realizing that animals they had thought were the same species, in fact, may not be! This shelled pteropod (Cavolinia uncinata) is considered the same species as the one in the previous photo. Because their fleshy parts look so different, however, Bush is analyzing each specimen’s genetic code to establish whether they really are the same species.
This string of eggs shot out of Cavolinia uncinata when it was being observed under the microscope. The eggs are attached to one another in a gelatinous mass, and, had they not been self-contained in a petri dish, would have floated through the water until the new pteropods emerged as larvae. Their reproduction methods aren’t well studied, but we know that pteropods start off as males and once they reach a certain size switch over to females. This sexual system, known as sequential hermaphroditism, may boost reproduction because bigger females can produce more eggs.
This pteropod (Limacina helicina) has taken a beating from being pulled through a trawl net: you can see the broken edges of its shell. An abundant species with black flesh, each of these sea butterflies are the size of a large grain of sand. In certain conditions they “bloom” and, when fish eat too many, the pteropod’s black coloring stains the fishes’ guts black.
Not only is the inside of this shell home to a pteropod (Clio recurva), but the outside houses a colony of hydroids—the small pink flower-like animals connected by transparent tubing all over the shell. Hydroids, small, predatory animals related to jellyfish, need to attach to a surface in the middle of the ocean to build their colony, and the tiny shell of Clio is the perfect landing site. While it’s a nice habitat for the hydroids, this shell probably provides less than ideal protection for the pteropod: the opening is so large that a well equipped predator, such as larger shell-less pteropods, can likely just reach in and pull it out. “I would want a better house, personally,“ says Osborn.
Gymnosomes are pteropods that lack shells and have a diet almost entirely composed of shelled pteropods. This species (Clione limacina), exclusively feeds on Limacina helicina (the black-fleshed pteropod a few slides back). They grab their shelled relative with six tentacle-like arms, and then use grasping jaws to suck their meal out of the shell.
This post was written by Emily Frost and Hannah Waters. Learn more about the ocean from the Smithsonian’s Ocean Portal.