September 17, 2013
“Call me Migaloo,” would start the memoir of the most famous white humpback whale out there. He’s not quite from the pages of Moby Dick—Herman Melville’s white whale was a sperm whale and not entirely white—but Migaloo still makes quite a splash when he lifts his head or tail above the waves.
First spotted in 1991, he’s been seen more than 50 times since, including a few times around the Great Barrier Reef this summer. But the probable-but-unconfirmed spotting by Jenny Dean, a Queensland, Australia native, takes the cake. A few weeks ago, she captured Migaloo breaching in a spectacular photo, showcasing the whale’s bright whiteness that nearly looks photoshopped.
But what’s the deal with Migaloo and white whales? Let us ocean enthusiasts from the Smithsonian Ocean Portal answer your questions.
What do we know about Migaloo?
In the past 22 years since whale watchers first spotted the exceedingly social Migaloo—so-called after the Aboriginal word for “white fella”—scientists have been able to learn a bit about him. They think he was around 3-5 years old when first spotted, which makes him 25-27 now. Barring an unfortunate accident, he may have another 50 years ahead of him, although scientists don’t know for sure how long humpback whales live because they don’t have teeth—like tree rings, analyzing concentric layers in teeth is a common way to measure age in mammals.
They know he’s a male from his song. While both male and female humpback whales produce sound, only males sing the melodic humpback songs that long ago captured our imaginations. In 1998, researchers first recorded Migaloo singing—and his knack for melody gave it away.
His maleness was further confirmed by DNA after researchers from Lismore, Australia’s Southern Cross University, collected skin samples from Migaloo in 2004.
Are white humpbacks rare?
As far as we know, exceedingly so. Besides Migaloo, there are three other known white humpbacks. Willow lives up in the Arctic and was spotted along the coast of Norway in 2012. Meanwhile, Bahloo lurks in Migaloo’s territory in the Great Barrier reef, first seen in 2008. But these two are not as gregarious as Migaloo, rarely showing their faces.
The other known white humpback is a calf first seen swimming around the Great Barrier Reef in 2011. Unofficially named “Migaloo, Jr.,” the calf is not known to be the child of Migaloo—in fact, the two whales may not even be related. If a DNA sample from the calf is obtained someday, they could compare it with Migaloo’s genetic profile to find out.
There probably are more white whales out there, however. These are just the ones that have surfaced near people with cameras. Two years ago, an unknown white whale washed up on a beach, and if you dig around on the web, you can find even more.
How do we know these aren’t the same white whale?
In the case of Migaloo, Jr., it’s pretty obvious: he’s much smaller than the Migaloo Australians are so familiar with.
Bahloo and Migaloo hang out in the same area and, because Bahloo rarely shows its face, you could argue that the two are actually the same whale. But photos taken in 2010 showed a few black spots on Bahloo’s head and tail, differentiating it from Migaloo. Willow also has black patterns on the underside of its tail, making Migaloo the only documented all-white whale. These patterns and markings are distinct for each whale, white or otherwise, allowing researchers to track the creatures through detailed observations.
Why is he white anyway?
Many articles describe Migaloo and the other white whales as albino. But making that diagnosis is easier said than done.
Albinism is a genetic disorder in which the protein tyrosinase, which helps to produce the pigment melanin, is completely absent or damaged by a variety of possible mutations. Fully albino animals and people have no melanin whatsoever; they are white or pink from head to toe, including their eyes.
Willow and Bahloo are not albino: they have black spots or patches on their bodies. It’s more likely that they have leucism, a condition where all pigment types are lost in patches of cells.
Even though Migaloo is all white, scientists are skeptical that he is albino because he doesn’t have red or pink eyes—like other humpbacks, he has brown eyes. Instead, he’s considered the more conservative “hypo-pigmented,” describing a generic loss of skin color. It’s also possible that Migaloo is leucistic.
The Southern Cross University researchers could analyze his DNA for different genetic variants associated with pigment disorders to pinpoint the exact form. But there are many variants and, as Megan Anderson, who originally tested Migaloo’s DNA, said in a press release, “It’s going to be a long and complex process to test for albinism in this humpback whale as it has not ever been done before.”
And what about the calf? There isn’t enough known about it to be sure.
Are there other white whales that aren’t humpbacks?
Yes! These skin disorders are not exclusive to humpbacks. There have been several other wild spottings of white whales recently.
A white right whale calf (incorrectly described as albino) was filmed last year off the coast of Chile by a group of surfers. Last April, researchers spotted a white killer whale off the coast of Alaska, and they named it “Iceberg.” And a truly albino pink dolphin has been seen around Florida and the Gulf of Mexico repeatedly over the years.
In fact, whales aren’t the only creatures that can lack pigment. A plethora of other all-white examples—such as koalas, penguins, and gorillas—can be found throughout the animal kingdom.
August 5, 2013
People have been fascinated and terrified by sharks for thousands of years, so you would think that we know a fair bit about the roughly 400 named species that roam the ocean. But we have little sense of how many sharks are out there, how many species there are, and where they swim, let alone how many existed before the advent of shark fishing for shark fin soup, fish and chips, and other foods.
But we are making progress. In honor of Shark Week, here’s an overview of what we have learned about these majestic citizens of the sea in the past year:
1. Sharks mostly come in shades of gray, and it’s likely that they only see that way as well. Now, that knowledge is being put to use to protect surfers and swimmers offshore. In 2011, researchers from the University of Western Australia found that, out of 17 shark species tested, ten had no color-sensing cells in their eyes, while seven only had one type. This likely means that sharks hunt by looking for patterns of black, white and grey rather than noticing any brilliant colors. To protect swimmers, whose bodies often look like a tasty seal from below, the researchers are working with a company to design wetsuits that are striped in colorblocked disruptive patterns. One suits will alert sharks that they aren’t looking at their next meal, and a second suit that will help camouflage swimmers and surfers in the water.
2. The thresher shark has a long, scythe-shaped tail fin that scientists long-suspected was used for hunting, but they didn’t know how. This year, they finally filmed how the thresher shark uses it to “tail slap” fish, killing them on impact. It herds and traps schooling fish by swimming in increasingly smaller circles before striking the group with its tail. This strike usually comes from above instead of sideways, an unusual technique that allows the shark to stun multiple fish at once—up to seven, the study found. Most carnivorous sharks only kill one fish at a time and so are comparatively less efficient.
3. How many sharks do people kill each year? A new study published in July 2013 used available shark catch information to estimate the global number—a staggering 100 million sharks killed every year. Although the data are incomplete and often do not include those sharks whose fins are removed and bodies are thrown back to sea, this is the most accurate estimate to date. Slow growth and low birth rates of sharks mean that they are not able to repopulate fast enough to catch up with the loss.
4. The 50-foot giant megalodon shark is a staple of shark week, reigning as the great white’s larger and even more terrifying ancestor. But a new fossil discovered in November turns that supposition on its head: it looks like the megalodon isn’t a great white shark ancestor after all, but is more closely related to the fish-munching mako sharks. The teeth of the new fossil look more like great white and ancient mako shark teeth than megalodon teeth, which also suggests that great whites are more closely related to mako sharks than previously thought.
5. Sharks are worth more alive in the water than dead on the plate (or bowl). In May, researchers found that shark ecotourism ventures—such as swimming with whale sharks and coral reef snorkeling—bring in 314 million U.S. dollars globally every year. What’s more, projections show that this number will double in the next 20 years. In contrast, the value of fished sharks is estimated at 630 million U.S. dollars and has been declining for the past decade. While dead sharks’ value terminates after they are killed and consumed, live sharks provide value year after year: in Palau, an individual shark can bring up to 2 million dollars in benefits over its lifetime from the tourist dollars that pour in just so that people can view the shark up close. One citizen science endeavor even has snorkeling travelers snapping photos of whale sharks in an effort to help researchers. Protecting sharks for future ecotourism endeavors just makes the most financial sense.
6. Bioluminescence isn’t just for jellyfish and anglers: even some sharks are able to light up to confuse predators and prey alike. Lanternsharks are named for this ability. It’s been long known that their bellies light up to blend in with sunlight shining down from above, an adaptation known as countershading. But in February, researchers reported that lanternsharks also have “lightsabers” on their backs. Their sharp, quill-like spines are lined with thin lights that look like Star Wars weaponry and send a message to predators that, “if you take a bite of me, you might get hurt!”
7. What can an old sword tell us about sharks? Far more than you might expect—especially when those swords are made of shark teeth. The swords, along with tridents and spears collected by Field Museum anthropologists in the mid-1800s from people living in the Pacific’s Gilbert Islands, are lined with hundreds of shark teeth. The teeth, it turns out, come from a total of eight shark species—and, shockingly, two of these species had never been recorded around the islands before. The swords give a glimpse into how many more species once lived on the reef, and how easy it is for human memory to lose track of history, a phenomenon known as “shifting baselines.”
8. Sharks know some pretty neat tricks even before they’re born. Bamboo shark embryos develop in egg cases that float on the high seas, where they are vulnerable to being eaten by all manner of predators. Even as developing embryos, they can sense electric fields in the water given off by a predator—just like adults. If they sense this danger nearby they can hold still, even stopping their breathing, so they won’t be noticed in their egg cases. But for sand tiger shark embryos, which develop inside the mother, their siblings can pose the biggest threat—the first embryos to hatch from eggs, at just roughly 100 millimeters long, will attack and devour their younger siblings.
9. Shark fin soup has been a delicacy in China for hundreds of years, and its popularity has only increased in the last several decades with the country’s growing population. This increasing demand has heightened the number of sharks killed every year, but the expensive dish may be losing some fans.
Even before last year’s Shark Week, the Chinese government banned the serving of shark fin soup at official state banquets—and the conversation hasn’t died down since. Countries and states banning the trade of shark fins and regulating the practice of shark finning have made headlines this year. And just a few weeks ago, New York Governor Andrew Cuomo signed a ban of the possession and sale of shark fins in the state that will go into effect in 2014.
10. Shark fin bans aren’t the only method of protecting sharks. The island nations of French Polynesia and the Cook Islands created the largest shark sanctuary in December of 2012—protecting sharks from being fished in an area of over 2.5 million square miles in the south Pacific Ocean. And member countries of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) voted to place export restrictions on five species of sharks in March 2013. Does this mean that the general perception of sharks is changing for the better and that the public image of sharks is veering away from its “Jaws” persona? That, in essence, is up to you!
–Emily Frost, Hannah Waters and Caty Fairclough co-wrote this post
July 11, 2013
When most people think about organisms growing on the seafloor around Antarctica (if they think of them at all), a few short words come to mind: cold, slow, and dull. But under the right conditions, seafloor life on Antarctia’s continental shelf can grow very quickly, according to new research published today in Current Biology. The collapse of ice shelves in the Antarctic over the past two decades due to warmer waters bathing their undersides has already changed seawater conditions enough to allow typically slow-growing communities of glass sponges to sprout up under the more transient sea ice that has replaced the shelf.
“These things aren’t as unexciting as we thought; they are actually very dynamic,” says polar ecologist James McClintock of the University of Alabama, who was not involved in the research. “The idea that they [glass sponges] could recruit and grow rapidly when these ice shelves break up is exciting, and suggests that the seafloor is going to change more quickly than we imagined.”
Glass sponges are the architects of the most diverse community on the seafloor under ice shelves. Like corals, glass sponges provide habitat for many other organisms. Their basket-like inner cavities are rare nurseries in the cold water, and small marine isopods, juvenile starfish, brittle stars, and even fish eggs have been found inside. As they die, they leave behind silica mats meters deep on the seafloor, providing prime substrate for crinoids, anemones, and other sponges to settle and grow. Also like corals, glass sponges grow slowly. Most grow only two centimeters each year, which makes the largest ones hundreds of years old.
Food scarcity is the reason for this slow growth. Antarctic waters have a very short growing season just weeks long, when sunlight and warmer water foster blooms of phytoplankton. During this brief period, phytoplankton feeds zooplankton, and waste products from the latter organisms feed bacteria and animals (like glass sponges) that filter particles and bacteria from the water. Even how much of that bounty an animal receives depends on whether it has settled in a current carrying food–or if those manna-bringing currents are blocked by ice. That said, it’s no surprise that, with so little food available, most organisms on the seafloor grow very slowly.
Ice also poses a hazard to life on the Antarctic seafloor. Icebergs and other types of sea ice, if they encounter shallower waters from where they calved, can dig ditches into the seafloor up to 350 meters wide and 15 meters deep, obliterating any living organisms from the area. Ice crystals (known as anchor ice) can grow on non-moving objects such as sponges, rocks and seaweed, eventually causing them to float up from the seafloor and merge with the ice ceiling. Additionally, brinicles, icy fingers of saltwater, shoot down from frozen ice at the surface, killing everything they touch as they spread across the seafloor.
But the past couple decades have seen changes to the ice cover in the Antarctic. Two large ice shelves known as Larsen A and Larsen B collapsed in 1995 and 2002 respectively. This freed more open water for phytoplankton to bloom, left more seafloor area free from regular iceberg scraping, and potentially altered how warm water and food circulate through the area. But given the slow pace of life in Antarctica, scientists weren’t expecting to find much when in 2011 they cut through the transient sea ice to survey the
seafloor once beneath the Larsen A ice shelf . Much to their surprise, they discovered that communities of small glass sponges had sprung up in the four years since their last visit.
In fact, the numbers of glass sponges had doubled, many belonging to smaller species that are not as common on older Antarctic sponge reefs. And the researchers saw a large increase in the number of sponges between 50-100 square centimeters in volume, suggesting that the young sponges had grown very quickly—and certainly more quickly than just two centimeters a year.
The sudden availability of free space and an influx of food likely explain how these sponges were able to grow so quickly. But where did this extra food come from? Paul Dayton of the Scripps Institution of Oceanography, who studied the ecology of Antarctica’s surrounding sea floor for many years but was not involved in this study, hypothesizes that the melting of the ice shelves increased currents, waves and wind in the area, stirring up the seafloor and resuspending particles and bacteria for the sponges to eat.
The study of the growth of one community in one part of the Antarctic may seem small. But it’s an example of how we can’t predict how ecosystems are going to react to climate change. It’s possible that glass sponges will be “winners,” able to grow better in the particle-heavy water mixed up by currents, or it may just be a short-term change. “I personally see this more as a pulse than [a community] being taken over by glass sponges,” says Dayton. “But with the huge changes coming down as a result of warming and loss of sea ice, it very well could result in a massive change in the Antarctic benthic community.”
April 25, 2013
Penguins seem a bit out of place on land, with their stand-out black jackets and clumsy waddling. But once you see their grace in the water, you know that’s where they’re meant to be–they are well-adapted to life in the ocean.
1. Depending on which scientist you ask, there are 17–20 species of penguins alive today, all of which live in the southern half of the globe. The most northerly penguins are Galapagos penguins (Spheniscus mendiculus), which occasionally poke their heads north of the equator.
2. While they can’t fly through the air with their flippers, many penguin species take to the air when they leap from the water onto the ice. Just before taking flight, they release air bubbles from their feathers. This cuts the drag on their bodies, allowing them to double or triple their swimming speed quickly and launch into the air.
4. Penguins don’t wear tuxedos to make a fashion statement: it helps them be camouflaged while swimming. From above, their black backs blend into the dark ocean water and, from below, their white bellies match the bright surface lit by sunlight. This helps them avoid predators, such as leopard seals, and hunt for fish unseen.
5. The earliest known penguin fossil was found in 61.6 million-year old Antarctic rock, about 4-5 million years after the mass extinction that killed the dinosaurs. Waimanu manneringi stood upright and waddled like modern day penguins, but was likely more awkward in the water. Some fossil penguins were much larger than any penguin living today, reaching 4.5 feet tall!
6. Like other birds, penguins don’t have teeth. Instead, they have backward-facing fleshy spines that line the inside of their mouths. These help them guide their fishy meals down their throat.
7. Penguins are carnivores: they feed on fish, squid, crabs, krill and other seafood they catch while swimming. During the summer, an active, medium-sized penguin will eat about 2 pounds of food each day, but in the winter they’ll eat just a third of that.
8. Eating so much seafood means drinking a lot of saltwater, but penguins have a way to remove it. The supraorbital gland, located just above their eye, filters salt from their bloodstream, which is then excreted through the bill—or by sneezing! But this doesn’t mean they chug seawater to quench their thirst: penguins drink meltwater from pools and streams and eat snow for their hydration fix.
9. Another adaptive gland—the oil (also called preen) gland—produces waterproofing oil. Penguins spread this across their feathers to insulate their bodies and reduce friction when they glide through the water.
10. Once a year, penguins experience a catastrophic molt. (Yes, that’s the official term.) Most birds molt (lose feathers and regrow them) a few at a time throughout the year, but penguins lose them all at once. They can’t swim and fish without feathers, so they fatten themselves up beforehand to survive the 2–3 weeks it takes to replace them.
11. Feathers are quite important to penguins living around Antarctica during the winter. Emperor penguins (Aptenodytes forsteri) have the highest feather density of any bird, at 100 feathers per square inch. In fact, the surface feathers can get even colder than the surrounding air, helping to keep the penguin’s body stays warm.
12. All but two penguin species breed in large colonies for protection, ranging from 200 to hundreds of thousands of birds. (There’s safety in numbers!) But living in such tight living quarters leads to an abundance of penguin poop—so much that it stains the ice! The upside is that scientists can locate colonies from space just by looking for dark ice patches.
13. Climate change will likely affect different penguin species differently—but in the Antarctic, it appears that the loss of krill, a primary food source, is the main problem. In some areas with sea ice melt, krill density has decreased 80 percent since the 1970s, indirectly harming penguin populations. However, some colonies of Adelie penguins (Pygoscelis adeliae) have grown as the melting ice exposes more rocky nesting areas.
14. Of the 17 penguin species, the most endangered is New Zealand’s yellow-eyed penguin (Megadyptes antipodes): only around 4,000 birds survive in the wild today. But other species are in trouble, including the erect-crested penguin (Eudyptes sclateri) of New Zealand, which has lost approximately 70 percent of its population over the past 20 years, and the Galapagos penguin, which has lost more than 50 percent since the 1970s.
Learn more about the ocean from the Smithsonian’s Ocean Portal.
March 29, 2013
If you were to hit the seafloor and continue to travel down, you’d run into an ecosystem unlike any other on earth. Beneath several hundred meters of seafloor sediment is the Earth’s crust: thick layers of lava rock running with cracks that cover around 70% of the planet’s surface. Seawater flows through the cracks, and this system of rock-bound rivulets is enormous: it’s the largest aquifer on earth, containing 4% of global ocean volume, says Mark Lever, an ecologist who studies anaerobic (no-oxygen) carbon cycling at Aarhus University in Denmark.
The sub-seafloor crust may also be the largest ecosystem on earth, according to a new study by Lever, published this month in Science. For seven years, he incubated 3.5 million-year old basalt rock collected from 565 meters below the ocean floor–the depth of nearly two stacked Eiffel towers–and found living microbes. These microbes live far away from the thriving bacterial communities at mid-ocean ridges, and survive by slowly churning sulfur and other minerals into energy.
But just how big is this chemically-fueled ecosystem that survives entirely without oxygen? If the results from his sample, collected from below the seafloor off the coast of Washington state, are similar to those found across the planet, then diverse microbial communities could survive throughout the ocean’s crust, covering two-thirds of the earth’s surface and potentially going miles deep.
The sub-seafloor crust has plenty of space and energy-rich minerals–a welcoming potential habitat for a large microbial community–“but we have no idea what the ecosystem looks like,” says Julie Huber, a microbial oceanographer at the Marine Biological Laboratory in Woods Hole, Massachusetts. “Mark’s evidence would point to it being a very different world.”
Microbes that get their energy from minerals, rather than from sunlight, are far from rare. The most well known of these so-called chemoautotrophic or chemosynthetic bacteria are those found at hydrothermal vents in the deep sea. Some of these bacteria live symbiotically with giant tubeworms, mussels and clams, providing chemically-produced energy to these larger organisms as they “breathe” the sulfur-rich water erupting from the vent–not unlike how plants convert sunlight into energy at the surface. Chemosynthetic microbes are also found in the rotting and oxygen-poor muck of salt marshes, mangroves and seagrass beds—“any place you’ve got stinky black mud, you can have chemoautotrophy,” says Chuck Fisher, a deep-sea biologist at Pennsylvania State University in College Park.
But what makes Lever’s sub-seafloor microbes different is that they don’t use any oxygen at all. The symbiotic bacteria at hydrothermal vents are often described as “life without sunlight,” but they still rely on sunlight indirectly by using sun-produced oxygen in the chemical reaction to generate energy. Chemosynthetic microbes in salt marshes feed on decomposing plants and animals, which got their energy from sunlight. Even deep-sea sediment is accumulated from an assortment of dead animals, plants, microbes and fecal pellets that relies on light energy.
The oceanic crust microbes, on the other hand, rely entirely on
non-oxygen-containing molecules derived from rock and completely removed from photosynthesis, such as sulfate, carbon dioxide and hydrogen. “In that sense it’s a parallel universe, in that it runs on a different type of energy,” says Lever. These molecules provide a lot less energy than oxygen, creating a sort of microbial slow food movement. So instead of dividing and growing quickly like many oxygen-based bacteria, Fisher suspects that microbes in the Earth’s crust may divide once every hundred or thousand years.
But just because they’re slow doesn’t mean they’re uncommon. “There are lots of data that there is a large, very productive biosphere under the surface,” says Fisher.
In addition, microbial population sizes in different areas of the crust may vary greatly, Huber notes. Through her studies on the fluid found between the cracks in the crust, she says that in some areas the fluid contains about the same number of microbes as standard deep-sea water collected at ocean depths of 4,000 meters (2.5 miles): around 10,000 microbial cells per milliliter. In other regions, such as at the Juan de Fuca Ridge in the Pacific Ocean where Lever found his microbes, there are fewer cells, around 8,000 microbes per milliliter. And in other regions, such as in non-oxygenated fluid deep in hydrothermal vents, there can be around 10 times more.
It’s not just the number of microbes that vary depending on location–it’s possible that different microbial species are found in different types of crust. “Different types of rock and different types of chemistry should result in different types of microbes,” says Andreas Teske, a deep-sea microbial ecologist at the University of North Carolina at Chapel Hill and co-author on Lever’s paper. The Juan de Fuca Ridge is a relatively hot area bursting with new rock, which tends to be made of more reactive minerals and thus able to provide more energy. Other parts of the crust are older, composed of different minerals, and cooler. And, in some regions, oxygenated water reaches down to the cracks.
It’s this infiltrating seawater that keeps this sub-seafloor ecosystem from existing on a completely separate plane from our oxygenated one. “The crust plays a significant role in influencing the chemical composition of the ocean and the atmosphere, ultimately influencing [nutrient] cycles on earth,” says Lever. Some of the compounds created by oceanic crust microbes from rock are water soluble, and will eventually enter the ocean. Sulfur, for example, is present in magma—but after the microbes use it for energy, it’s converted to sulfate. Then it dissolves and becomes an important nutrient in the ocean food chain.
Lever’s find of a microbial community in the crust could catalyze the scientific community to answer these questions. For example, what kinds of microbes are found where, do they interact through interconnected cracks in the rock, and what role do they play in mineral and nutrient cycling? In some ways, it’s very basic exploratory work. “A lot of what we do on the seafloor is similar to what we’re doing on Mars right now,” says Huber. “Controlling [NASA’s Mars Rover] Curiosity is very similar to operating an ROV under the ocean.”