What is it? A beaded necklace? Red blood cells? No, it’s the Portuguese Man o’War (Physalia physalis), magnified 30 times. Though it resembles a jellyfish, the Portuguese Man o’War is a siphonophore, a colony of organisms that work together. The sting of the venom in the tentacles’ nematocysysts is incredibly painful, though rarely deadly. This photo, taken by Alvaro Migotto of the University of São Paulo in Brazil, won 6th prize in the 2009 Olympus BioScapes Interational Digital Imaging Competition.
Notorious for its painful, powerful sting, the Portuguese Man o’ War has a gas-filled floating chamber that supports the tentacles, which bear sting cells. Shown are the pink batteries of stinging cells and a delicate muscular band responsible for the high contractibility of the tentacles.
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My colleague Megan Gambino visited the Smithsonian Tropical Research Institute earlier this year to watch coral spawn. A report appears in the December issue of the magazine, and she also blogged about the experience over at Around the Mall. We asked her if anything interesting got left out of her previous reports. Yes, lots, she replied, and wrote this:
This past September, I joined marine scientist Nancy Knowlton, of the National Museum of Natural History; her colleague Don Levitan, of Florida State University; and a crew of research divers on their annual coral spawning trip. Just days after the September full moon, a mass coral spawning happens at their study site, a 260-foot arc of reef about 20 minutes by boat from the Smithsonian Tropical Research Institute’s field station in Bocas del Toro, Panama, and each year, since 2000, they have been there to collect data.
Knowlton, a renowned coral reef biologist, has been called Dr. Doom for the grim, but realistic, picture she paints of reefs suffering worldwide. (Her husband Jeremy Jackson, also a prominent marine scientist, is Dr. Gloom.) But she has also been billed as a savior. Vanity Fair, in its May 2007 “Green Issue,” called her a “mind aquatic” that our future, and our lives, may depend on. Along with other marine scientists, Knowlton has been trying to help reefs survive by better understanding coral reproduction.
A close up view of a Montastraea franksi colony spawning (credit: NOAA)
Early in Knowlton’s career, the assumption was that most coral colonies picked up sperm and brooded embryos internally—and some do. But in 1984, Science published the first description of a dramatic mass-spawning event witnessed on Australia’s Great Barrier Reef. Around that time, research biologists were observing the phenomenon in the Caribbean as well. From this, scientists deduced that the majority of corals—called “broadcast spawners”—actually reproduce in this way. Many are hermaphrodites, meaning they release gamete bundles containing both eggs and sperm. But, unable to self-fertilize, they synchronize their spawning with neighboring corals. The more scientists study the annual orgies, the better they have become at predicting when they will happen. The corals appear to use three cues: the full moon and sunset, which they can sense through photoreceptors; and, most likely, a chemical that allows them to smell each other spawning.
Knowlton’s team has been monitoring three closely related coral species—all dominant reef builders in the Caribbean—called the Montastraea annularis complex. What they have found is that M. franksi, one of the species, spawns on average 100 minutes after sunset and M. annularis and M. faveolata, the other two, follow about 100 minutes later, typically five and six days after the September full moon. Over the nine years of the project, the researchers have spotted, flagged, mapped and genetically identified over 400 spawning coral colonies.
As with any long-term study, the scientists’ questions have evolved. At first, they wondered how the three species, spawning at or close to the same time, didn’t hybridize. Their lab tests show that of the three, the early spawner and one of the later spawners are reproductively compatible. But they have found that the hour and a half or so between the species’ peak spawning times is enough time for the gametes to disperse, dilute, age and effectively be rendered unviable. In fact, their data indicates that if corals spawn just 15 minutes out of sync with the majority, their chance at reproductive success is greatly reduced. The looming question now is, what will happen to fertilization rates as coral colonies become few and far between?
By the third of four nights of diving (and no spawning), the suspense was building. The divers playfully suggested playing Barry White as mood music and gorging, pre-dive, on aphrodisiacs like oysters and strawberries.
Around 7:25 PM, just as everyone was slinking into their wetsuits, sea worms called palolo worms began spawning around the boat. The worms break in half and the tail section swims to the surface and releases eggs or sperm in a cloud of bioluminescence.
“This is it,” said Knowlton. “Everybody’s in the mood for sex.”
The water got buggy and electric, and like clockwork, the coral colonies started spawning around 8:20, one triggering another triggering another. The tapioca-like gamete bundles, about two millimeters in diameter and containing about 100 eggs and one million sperm, lifted in unison, slowly drifting to the surface.
The dive team observed 162 different coral colonies set or spawn, and the next night, they saw another 189. Knowlton surfaced that final night, exhilarated. What did you think? She asked each of the divers. Amazing, huh? She didn’t want to get out of the water and grabbed hold of the side of the boat, arching her back, her eyes cast toward the sky. Even the stars looked like gametes.
Last week, the U.S. government took the brown pelican (Pelecanus occidentalis) off the endangered species list. The birds’ numbers had been depleted first by feather hunters and then by the pesticide DDT. But the pelicans made a comeback, starting with the 1972 ban on DDT, and now there are more than 650,000 in North and Central America. (The birds are doing so well, one even took out a Bugatti Veyron last week, though that may have been due instead to the idiot behind the wheel talking on his cell phone.)
To celebrate the brown pelican’s success, here are eight more species that came back from the brink:
American alligator in a Louisiana swamp (courtesy of flickr user Arthur Chapman)
Alligator leather is not only tough and durable but also pretty attractive. The popularity of alligator hides for leather made hunting of them common in the early 20th century. Even after it was outlawed, poaching continued into the 1970s. But laws that control the movement of hides and the creation of commercial alligator farms have taken pressure off the wild population, which now numbers a million or more.
Like the brown pelican, our national bird nearly got wiped out in the mid-20th century by DDT, which caused female eagles to produce eggs with shells too thin to withstand her weight. With DDT banned in the United States and Canada, the bird has made a full recovery and was taken off the endangered species list in 2007. They remain protected from hunting, though, under the 1940 Bald Eagle Protection Act.
There once were perhaps 20 to 30 million bison (a.k.a. buffalo) roaming the plains of North American. Hunting in the 19th century drove their numbers down to just a few hundred by the 1880s. Only the skins were saved; their carcasses were left to rot. A few small herds survived, though, and the bison population now numbers around 350,000. Most of them, however, are raised on farms for meat. There are only four herds, including the one in Yellowstone National Park, that have not been genetically diluted by interbreeding with cattle.
Their population in Suriname has been dwindling due to habitat destruction and the illegal pet trade. However, captive breeding programs in several zoos have been successful, and scientists plan to reintroduce the frog to areas where they have disappeared.
A male Southern elephant seal (via wikimedia commons)
These large marine mammals, perhaps best know for their large schnoz, were nearly hunted to extinction for their blubber, which was made into oil. Large-scale hunting ended by the end of the 19th-century and the population recovered by the mid-20th, now numbering in the hundreds of thousands.
This 700-pound grouper likes to hang out on coral reefs. But once fishermen discovered how easy it was to spear the fearless fish, the groupers’ population began to dive. Bans on their fishing were put in place in the United States in 1990 and in the Caribbean in 1993. Though still classified as endangered, the goliath grouper’s numbers are rising.
It’s hard to blame people for wanting to kill a predatory creature that goes after your livestock or your pets. But the extirpation of the gray wolf from most of the United States led to unintended consequences for the environment, throwing ecosystems out of balance. A reintroduction program in the Rockies, however, has been largely successful.
Like the elephant seals, humpback whales were nearly wiped out by hunters who wanted their blubber (and also their baleen and flesh). Some 250,000 were killed in the 20th century alone. A ban on hunting, in place since 1966, has let the whale populations recover, and there are now around 80,000 distributed around the world’s oceans.
Amazon rainforest deforestation, courtesy of Flickr user Threat_to_Democracy
Here’s a roundup of the best of what I’ve been reading in the past couple of weeks:
Are global warming and deforestation too scary for Sesame Street?: A couple of years ago Sesame Workshop named these as adult topics too scary for young children. Instead they focus on teaching kids to respect the Earth. Climate change and deforestation are scary, and I’m okay with keeping them away from five-year-olds. Am I wrong?
One Giant Leap seen again: Bad Astronomer Phil Plait has images from the Lunar Reconnaissance Orbiter of the Apollo 11 landing site. You can even see the lunar lander footpads.
Pigs Prove to Be Smart, if Not Vain: Pigs successfully pass the mirror self-recognition test, a sign of cognition. But if pigs are smarter than we think, will we still eat them? (No bacon would be a bad thing.)
And though I had been looking forward to reading Superfreakonomics (having been a fan of Freakonomics), I’ve decided to skip it. I’ve now read several essays critical of their climate change chapter, but it’s the open letter on Real Climate from geophysicist Raymond T. Pierrehumbert that has convinced me that the Freakonomics team desperately needs a fact checker. I’d offer my services, but Smithsonian keeps me pretty busy.
While writing about the Falklands wolf last week and earlier about the Labrador duck, I was reminded that they are only two of the dozens, maybe hundreds, of creatures that have gone extinct in recent human memory (that is, the last few hundred years). Here are seven more creatures that exist only in pictures or as museum specimens:
A 17th-century Dutch drawing of a dodo (via Wikimedia commons)
The dodo has become synonymous with extinction. To “go the way of the dodo,” for example, means that something is headed out of existence. The three-foot-tall, flightless bird lived on the island of Mauritius in the Indian Ocean. They probably ate fruit. Though the birds did not fear humans, hunting was not a huge problem for the birds as they didn’t taste very good. More troublesome were the other animals that came with people—like dogs, cats and rats—that destroyed dodo nests. Human destruction of their forest homes was also a contributor to the dodo’s decline. The last dodo was seen on the island sometime in the late 1600s.
Georg Steller's drawing of the sea cow that bears his name (via Wikimedia commons)
Georg Steller first described his sea cow in 1741 on an expedition to the uninhabited Commander Islands off the coast of Kamchatka. The placid sea creature probably grew as big as 26 feet long and weighed around 8 to 10 tons. It fed on kelp. Just 27 years after Steller’s discovery, however, it was hunted to extinction.
Audubon's painting of great auks (via Wikimedia commons)
Millions of these black-and-white birds once inhabited rocky islands in some of the coldest parts of the North Atlantic, where the sea provided a bounty of fish. Though their population numbers probably took a hit during the last Ice Age, it was the feathers that kept them warm that led to their downfall. The soft down feathers were preferred pillow filling in Europe in the 1500s and in North America in the 1700s. The dwindling birds were further doomed when their eggs became a popular collector’s item. The last live auk was seen in Newfoundland in 1852.
Martha, the last passenger pigeon (via Wikimedia commons)
The passenger pigeon was once the most numerous bird species in North America, making up 25 to 40 percent of all birds on the continent. There were as many as 3 to 5 billion of them before the Europeans arrived. They would migrate in huge flocks consisting of millions of birds. In the 1800s, however, they became a popular food item. Tens of thousands could be killed in a day. By the end of that century, when laws were finally passed to ban their hunting, it was too late. The last wild bird was captured in 1900. Martha, the last of her kind, died in 1914 at the Cincinnati Zoological Garden.
Audubon's painting of Carolina parakeets (via Wikimedia commons)
The eastern United States once had its own native parrot, the Carolina parakeet. But farmers cut down their forests and made fields, and then killed the birds for being pests. Some birds were taken so that their feathers could adorn ladies’ hats, and others became pets. The last wild parakeet was killed in 1904 in Florida. The last captive bird, which oddly enough lived in the same cage in which the passenger pigeon Martha died (above), died in 1918.
Captive thylacines in Washington, D.C., c. 1906 (via Wikimedia commons)
The thylacine wasn’t really a tiger, though it got that name for the stripes on its back. The largest carnivorous marsupial, it was once native to New Guinea, Tasmania and Australia. It had already become rare by the time Europeans found Australia, confined to the island of Tasmania. In the 1800s, a bounty was put on the species because it was a danger to the sheep flocks on the island. The last wild thylacine was killed in 1930, though some may have survived into the 1960s.
They lived in the Monteverde Cloud Forest Preserve in Costa Rica. Most of the year, they were hard to find, and scientists think they may have lived underground. But during the rainy season of April to June, they would gather in small, temporary pools to mate. The population crashed in 1987 due to a bad patch of weather and none have been seen since 1991. No one is sure what happened, but climate change, deforestation and invasive species have all been suggested as possible culprits.
That's not a polar bear, it's a "spirit bear" (courtesy wikipedia)
Generally, having white fur is only good if you live in a white environment. The arctic fox, for example, would probably be eaten pretty quickly if it lived in Florida. Likewise, black bears that inherit two copies of a recessive gene for a white coat tend not to live very long, becoming victims of wolves or grizzly bears.
Except on a few small islands in western Canada that lack wolves and grizzly bears. On those islands, 20 to 30 percent of the black bears are white. They are known as “spirit bears” or Kermode bears. Native American tradition from the region says that the spirit bears lived on the ice-covered landscape of times long ago. Scientists, however, have hypothesized that the white color is a more recent mutation that has become prevalent on these islands due to genetic drift.
Whenever the trait developed, it may have given the white bears some sort of advantage. In a new study, published in the Biological Journal of the Linnean Society, biologists from British Columbia started looking at the diet and foraging behavior of the white and black bears. Both types eat the same kind of food, and go after it in the same ways. The difference comes during the autumn salmon run. During the day, the white bears are about 20 percent more efficient in their fishing compared with the black bears. The biologists say that the white fur is less visible in the water during the day and the salmon are less likely to try to evade the white bears. The spirit bears are able to fatten up faster for winter, which translates to better survival.
It’s not all good news for theKermode bears of western Canada, however. As in many other places along the west coast of North America, the spirit bears’ salmon are on the decline.
Thomas Vignaud of Marseille, France took this photograph, labeled Young fish dart by a jellyfish in the sea, in the Mediterranean Sea in September 2007. With it, he won the Natural World Category of Smithsonian magazine’s 5th Annual Photo Contest.
Have you taken an amazing photograph? Hurry up and enter our 7th Annual Photo Contest. The deadline is Tuesday, December 1, 2009, at 2pm Eastern Standard Time (EST).
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Falkland sheep have no need to worry about wolves these days (courtesy of Flickr user ShimShamB)
When Charles Darwin’s reached the Falkland Islands on his famed voyage, he discovered there a “large wolf-like fox” found nowhere else in the world. “As far as I am aware,” he would later write in The Voyage of the Beagle, “there is no other instance, in any part of the world, of so small a mass of broken land, distant from a continent, possessing so large an aboriginal quadruped peculiar to itself.” The human population on the island, however, was quickly increasing and the canid’s numbers were dwindling. Darwin predicted the species would soon go the way of the dodo, and he was right. The species went extinct in 1876, killed off for its fur and to protect the sheep population.
Since Darwin’s time, scientists have puzzled over his wolf-like canid, now known as the Falklands wolf. The species was the only native terrestrial mammal found on the island; there were no mice or porcupines or deer. And the islands lie 300 miles from the mainland. Where did the wolf come from and how did it get to the Falklands? Could Native Americans have brought the wolves to the island?
To get a picture of the wolf’s history, scientists isolated DNA from four museum specimens of the Falklands wolf, including one that had been collected by Darwin himself. (Their study appears in Current Biology.) They compared the DNA of their specimens with that of other canids, including several South American species (foxes, the maned wolf, and the bush dog) and members of the Canis genus (which includes the gray wolf and coyotes). With the DNA data, they created a phylogenetic tree that let the scientists see which species were the most closely related to the Falklands wolf and when the Falklands wolf branched off as a new species (that is, when they became isolated on the islands).
The four museum specimens diverged from their closest relatives about 70,000 years ago, which the scientists think is when the species came to the Falkland Islands. That was during the last ice age and long before humans showed up in the area (nixing the Native American theory). The wolves probably floated to the islands on ice or logs or perhaps walked over a glacier. Once on the islands, they would have feasted on penguins, geese and pinnepeds.
The scientists now have a new mystery: The analysis revealed the maned wolf to be the Falklands wolf’s closest relative, but the two species diverged from each other over 6 million years ago, several million years before canids populated South America from the north. There aren’t yet any canid fossils from this time period—something to look for.
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