Martin Nweeia knows more about narwhals than almost anyone in the world. More specifically, he’s probably the world’s foremost expert on narwhal tusks. But Nweeia is only sort-of a marine mammal biologist. He’s actually a practicing dentist and a clinical instructor at the Harvard School of Dental Medicine. This guy knows from teeth. So, while it might seem weird that he studies narwhals, if you think about it, there’s some sense to his in-depth knowledge of these whales’ toothy protuberances. We chatted with Nweeia about why the narwhal tusk is one of the weirdest teeth in the world and what it’s like to wade into the arctic waters of Canada’s Northwest Territories with Inuit guides to get a closer look at the real-life unicorn of the sea.

What exactly is a narwhal?

It’s an arctic whale with an extraordinary tooth.

So, maybe it’s not so strange that you’re a dentist studying a whale...

For everybody else it’s unusual. For me it’s OK. At the heart of things I’m a curious kid. As I went through my dental education I was equally fascinated by people. I had a very strong interest in anthropology that went parallel with my interest in science. These two fields would intersect. For a long time I was interested in dental anthropology, but I happened on the narwhal because I used to give talks and give examples of how teeth would express themselves in nature.

The narwhal seemed like a good example of an unusual tooth. But it didn’t make sense to me. And the more I read about it the less sense it made.

Why doesn’t it make sense?

This is a whale that eats pretty big fish and when you look inside its mouth it has no teeth. If i’m eating large fish, that might require chewing and biting, why give up all those teeth and put all of the energy into growing one giant tusk?

But there are also lots of the little things that don’t make sense. When you think of teeth, on both sides of a mammal's bite you’d expect them to be the same size and have a mirror image morphology or shape. In narwhals it couldn’t be more opposite. It doesn’t even fall within any parameter of any creature ever known on the planet.

If you look at the narwhal’s, its tusk comes out of the left side. When you see photos of them, they angle their body so the tusk appears straight in alignment with the horizontal axis. But if you look at them still, clearly the tusk is coming from the left side. The tooth on the right side often stays embedded in the skull.

You’ve got a tooth on one side that’s between a foot and a foot and a half and on the other side it’s 9 feet. Even in the rare instance when the narwhal has two tusks, the right is usually less in length from the left. The erupted tusk is on the left side or on both sides, or none. Never on the right by itself.

The Fermi Paradox is endlessly fascinating to me. The paradox is simple--there are somewhere between 100 billion and 400 billion stars in our galaxy, cosmologically speaking our Sun is relatively young, and our species is brand new. If life is abundant in the universe, why haven't we heard from anyone else yet?

This article does a good job breaking down the possible reasons we haven't made contact yet. The explanations range from the macabre to the comical. Personally, I'm optimistic that the first species that developed interstellar travel hasn't been wiping out any other species that can potentially compete with them. I also would hope that we don't just live "far out in the uncharted backwaters of the unfashionable end of the Western Spiral Arm of the galaxy." Getting any resolution to the Fermi Paradox would frankly be terrifying, but it's a good excuse to spend a few minutes this weekend laying with your back on the ground and contemplating the infinite.

For over 500 year historians have wondered: where in the world is Christopher Columbus' lost ship? The Santa Maria was the largest of three ships to sail across the Atlantic on Columbus' first voyage, but the only one to sink.

In May, a well-known undersea explorer by the name of Barry Clifford announced he may have found the missing ship off the coast of Haiti. It's there that records say the Santa Maria hit reef and met its watery end. But if that turns out to be the case, don't expect to see the Santa Maria's salvaged remains on display in a museum anytime soon. Removing a wreck from the ocean floor – particularly a very old wreck such as this – is often the last thing that archaeologists and historians want to do.

An artist's interpretation of the grounding of the Santa Maria.

In 2001, the United Nations Educational, Scientific and Cultural Organization (UNESCO) published a document with the aim of strengthening the protection of so-called underwater cultural heritage sites – environments that have traces of human existence with cultural, historical or archaeological character, and have remained in water for at least 100 years.

As far as wrecks are concerned, "The preservation in situ of underwater cultural heritage shall be considered as the first option before allowing or engaging in any activities directed at this heritage," the document states. The short version is that leaving the ship and its artifacts where they were found – in situ – might actually do more to preserve and conserve the site than raising them from the water. But there are and have been exceptions.

"The principle is that, yes, you can still recover things if they're threatened," says Marc-André Bernier, chief underwater archaeologist for the government agency Parks Canada. "If there is a research question that you can only answer by excavation then it's justified. But the principle is that if it's somewhere, it has a sense in that place, so if you can, you should try to leave it there."

In other words, context is important. And once you excavate a shipwreck, you lose details about its history and fate. "The site or the shipwreck has a story to tell. And when you excavate it's like reading a book, which is the story of a ship. But the pages disappear as you read them," Bernier says. "And if you don't take notes and record everything, you're only relying on your memory."

But leaving a shipwreck in situ can sometimes be just as damaging as recovering the remains.

Researchers are totally obsessed with understanding sharks right now. One of the major reasons why is that the world’s most successful hunters have been elusive and difficult to study. They’re constantly on the move -- some species migrate thousands of miles every year. But thanks to all sorts of new technologies, and some innovative scientists finding unconventional ways to use that tech, shark behavior is finally starting to come into the light. Here’s a look at some of the more innovative ways scientists are using tech to study sharks.

Image credit: Carl Meyer

Underwater Cameras

Scientists may have captured and tagged some sharks, and observed their behavior from the surface of the sea, but very little is known about how they behave when no one’s looking. The least studied part of shark behavior, for example, is how they interact with each other or other species of shark. So Carl Meyer and his team at The University of Hawaii worked with Japanese company Little Leonardo to build cameras small enough to fit on a shark’s fin without hindering their movement.

What they found once the cameras were in the ocean shocked them. Local reef sharks -- just a few miles off the coast of their own research base -- were mingling with all sorts of different shark species, including Hammerheads. The team was able to see feeding behavior and even some frisky swimming as sharks chased around members of the opposite sex.

Above: Camera-equipped male sandbar shark swims in close proximity to the reef, startling reef fishes, before heading across open sand to find and pursue a female sandbar shark. Credit: University of Hawaii (Carl Meyer)/University of Tokyo (Katsufumi Sato)

Meyer calls the cameras “data flight recorders for sharks” and says that thanks to the research they now have the first true sharks-eye-view of the ocean. Going forward they’re hoping to gain a better understanding of sharks eating habits by seeing the hunt from the sharks’ perspective.

When was the last time you saw an image of Pluto? Think about it. You've probably seen renders and simulated images – but what about an actual, high-quality picture of the minor planet's surface? Don't feel bad if you're drawing a blank. Real pictures of Pluto just don't exist – none more than a few pixels in size, at least. Even with the best and most modern technology at our disposal today, we still can't produce a decent picture of the dwarf planet from here on Earth.

Artist's rendition of the surface of Pluto. Credit: ESO

But around this time next year, thanks to the New Horizons spacecraft launched in 2006, we'll finally catch our first high-quality glimpses of how the solar system's most distant celestial object actually looks.

The best pictures we currently have of Pluto date from 1994.

If you can believe it, the best pictures we currently have of Pluto date from 1994. And, really, they're only pictures in the most liberal sense: blurry, blown-up surface maps made from source images mere pixels across. Taken with the Hubble Space Telescope, the orbiting camera is only just powerful enough to resolve the planet's surface colour – "a complex-looking and variegated world with white, dark-orange and charcoal-black terrain" – making geological observations out of the question.

"To a close approximation, Pluto and the moon are the same size." explains Dr. Marc Buie, a staff scientist at the Southwest Research Institute, and part of the team that captured the planet's first Hubble images. "[But] Pluto is an awful lot farther away."

Image credit: NASA

In fact, from our planet's surface, Pluto is about 180,000 times smaller on the sky at that distance than the Earth's moon.

That hasn't given researchers much to go on – not in the visual wavelength, anyhow. But as you read this article, the New Horizons spacecraft is nearly 30 astronomical units from the sun – or, about the distance from the sun to earth multiplied by 30. Travelling at a rate of about 1 million miles each day, it is the fastest spacecraft ever built. Its primary mission is to image the surface of Pluto, its moons, and beyond, and it is now about 90% of the way to its long-awaited flyby in July 2015.

Aerospace technology is typically an incremental game of inches. Most new aircraft or spacecraft designs consist primarily of proven technologies sprinkled with a few new ideas to nudge the limits a little at a time. It is rare to unveil a design that leaps ahead by using numerous unproven concepts. The Lockheed SR-71 Blackbird was one very notable exception. First flown in 1964, the Blackbird was an aircraft so advanced that it still had no peers when it was retired 34 years later.

Photo credit: Lockheed Martin

What made the Blackbird so unique was its ability to fly very fast (Mach 3.3) and very high (85,000 feet). This performance allowed it to overfly nearly any area of the world and take surveillance photos with relative impunity. Intercepting fighter pilots could only shake their fists as the SR-71 flew high above their reach. To escape surface-to-air missiles, Blackbird pilots would just ease the throttles forward and outrun them.

Throughout its service life, the SR-71 was a very closely-guarded and coveted asset. Not only was it stuffed full of proprietary technology, it was also extremely expensive to purchase, maintain, and operate. The US Air Force wouldn’t let just anyone fly their prized machine. It implemented a very rigorous selection and training process for the pilots and Reconnaissance Systems Officers (RSO) that would fill the Blackbird’s seats.

Terry Pappas was part of an elite group of pilots chosen to fly the SR-71 Blackbird. (Photo courtesy Terry Pappas)

Terry Pappas was one of those pilots who earned the title “Habu” – the unofficial name given to the SR-71 and its flight crew in a nod to the venomous snake that the airplane is said to resemble. Pappas spent more than 5 years in the SR-71 program and flew numerous operational missions over hostile airspace. His book, SR-71, The Blackbird, Q&A, explains the full gamut of his time in the Blackbird.

Here are some of the most interesting bits I learned from his book, as well as a few follow-up questions I was able to ask Pappas directly.