SCIENCE LAB SPECIAL NATURE'S MIGHT

1.- Marine Mystery The Shark. On the beach. With a sword The first victim washed up in September 216. The police in Valencia, Spain, saw a blue shark ding in the surf. They called Jamie Pendes-Suay, who soon suspected foul play.

The shark had what looked like a bit of wood embedded in its head. He pulled out slid a broken fragment from a swordfish sword that had lanced straight through the victims brain.

'I thought it was crazy,'' said Penades Suay, a graduate student at the University of Valencia and a founder of LAMNA, a Spanish consortium that studies sharks. ''I was never sure if this was some kind of joke.''

But since then at least six more more sharks have washed up on Mediterranean coasts, each impaled with a similar murder weapon, almost always in the head.

Taken together these cases offer what may be preliminary scientific evidence of high-speed, high-stakes underwater duels that had previously been confined to fishermen's tales.

Historically, whalers, fishermen and scholars saw swordfish as gladiators. But modern scientists were skeptical.

''Now at least we have evidence that they might use it really as a weapon, intentionally,'' said Patrick Jambura, a graduate student at the University of Vienna.

2.- Making It Through The Arctic Night : On the tundra, musk oxen march to a different circadian drummer. 

In the different reaches of northeastern Greelnad, musk oxen amble across the tundra, grazing as they go. They need to gather enough energy to survive cold, dark winters.

Most creatures on the planet live in lock step with the planet's daily cycle of light and dark. there's a time of the day for eating, a time of day for sleeping, a time for digestion.

Researchers used GPS collars to track 19-free roaming musk oxen for up to three years, said Floris van Beest, an African ecologist at Aarhus University in Denmark and an author of a paper in Royal Society Open Science.

''We don't find very strong circadian rhythms,'' Dr. Van Beest said, meaning that the animals don't seem to be repeating themselves every 24 hours. Some oxen completely lose their patterns in the sunnier months, eating frequently but more or less at random. Veronique Greenwood

3.- Do-It-Yourself-Construction : Spider Silk is stronger than steel, and it forms entirely on its own.

Pound for pound, spider silk is stronger than steel and tougher than Kevlar. But it doesn't start out that way.

The silk starts out in a liquid form that is transformed as it is excreted by the spider. It doesn't just turn into a solid. The protein building blocks in silk, called spidroins, fold themselves and interlace, creating a highly organized structure.

This remarkable process of self-assembly is about as strange as a garden hose spitting out a stream of perfect snowflakes. Scientists have spent years trying to mimic it in the hopes that it will someday revolutionize construction of ultra-strong, sustainable materials.

''You can really generate materials with unique properties by exploiting this self-assembly process,'' said Ali Malay, a structural biologist and biochemist at the Riken Center for Sustainable Resource Science in Japan.

He doesn't have the process entirely figured out, but in a paper published in Science Advances, he and his colleagues lay out a new way to tackle the spider silk puzzle, mimicking its creation with chemical tools in the lab Katherine J. Wu.

The honor and serving of the Science Lab Special continues.