Saturday, September 27, 2014

Deadly beauty

The Portuguese man-of-war—a colonial organism related to the jellyfish—is infamous for its painful sting, but one photographer finds the beauty inside this animal's dangerous embrace.
For nearly two years, retired U.S. Navy combat photographer Aaron Ansarov has collected and photographed man-of-wars that wash up on a local Florida beach.

From NationalGeographic by Jane J. Lee

The Portuguese man-of-war is infamous for its painful sting, but one photographer finds the beauty inside this animal's dangerous embrace.

The vibrant hues and ethereal body of the Portuguese man-of-war entice people to take a closer look, but beware—to those who draw too near, this delicate creature delivers a painful sting.
Being built like a glass-blown ship at full sail is what gave the man-of-war its nautical name.
It’s also what enables the creatures to go where the wind takes them—even when that means foundering on the beach.
This is where professional photographer Aaron Ansarov encounters them.
A retired combat photographer for the U.S. Navy, Ansarov has been collecting and photographing man-of-wars from a local Florida beach for the past two years now.
“It’s an opportunity to explore a new world,” he says, and part of a wider photo project Ansarov started after he left the military in 2007.
(Read about his project in National Geographic magazine.)

A Division of Labor

Colors are what first caught Ansarov’s eye when he saw a Portuguese man-of-war washed up on a Florida beach.
Most people think only about their nasty sting, he says.
But there is another side to this predator that Ansarov wanted to get to know.
The animal is actually part of a group related to jellyfish called siphonophores.
What appears to be one organism in this group actually is a colony.
Instead of having specialized tissues that form organs, as in other animals, siphonophores are collections of genetically identical individuals specialized for different tasks.
Some form tentacles (banded strands at the top of the image), while others form feeding bodies (brown speckled parts near the bottom), floats, or reproductive structures.

Deadly “String of Pearls”

The tentacles of the man-of-war capture and immobilize prey like young fish, small shrimp, or tiny crustaceans called copepods.
In this image, the tentacles are the long, banded strands near the bottom that look like blue or purple strings of pearls.
The tentacles contain batteries of cells that house miniscule, hollow harpoons called nematocysts.
Those barbed harpoons act like hypodermic needles, enabling the man-of-war to inject a potent mix of venom into a victim.

A Matter of Circumstance

The man-of-war’s sting is deadly to small swimmers except for the man-of-war fish, which lives and feeds among the siphonophore’s tentacles (purple strands at left in the picture above), unharmed.
But the danger for people from the man-of-war’s venom depends on the victim’s age and where they’re stung, says Angel Yanagihara, a professor who studies toxins in the group containing siphonophores at the University of Hawaii in Honolulu.
Skin thickness varies in different parts of the body, and “women and children have thinner skin than men,” she says.
“If a child gets stung around the neck, it could potentially be a lethal event because so much of the venom can be injected into the bloodstream.”
However, if an adult man gets stung across the back, it might cause only an irritation similar to when splinters are stuck in the skin, she says.

A Deadly Cocktail

“There are many paths to destruction” among these creatures, Yanagihara says, and the Portuguese man-of-war employs them all in its venom.
One compound in the venom creates holes in a cell’s membrane, essentially killing it, she says.
Other compounds slowly break down the proteins and fats surrounding the cell, allowing the man-of-war to start digesting its prey on contact.

A Shared Meal

Once a man-of-war captures a meal, the tentacle brings its prey to one of several feeding bodies (the brown speckled structures across the center of the image above).
Since the “individuals” within the colony are all connected, after a stomach digests the meal, the nutrients get spread throughout the colony.
(Watch a video of Portuguese man-of-wars.)

Setting Sail

Portuguese man-of-wars ply the high seas aided by an asymmetrical, oblong-shaped float with ridges on top (center of image).
That float acts like a sail, allowing them to angle into the wind, says Casey Dunn, an evolutionary biologist specializing in siphonophores at Brown University in Providence, Rhode Island.
Using that sail to move around is an amazing way to make a living, says Dunn.
“Most siphonophores are sit-and-wait predators,” he says: They park themselves in one spot for a time and wait for prey to blunder into their tentacles.
In contrast, Portuguese man-of-wars move around the ocean via their sail-topped float, trailing tentacles that dangle an average of 30 feet (9 meters) down into the water.
While their surface-skimming existence enables Portuguese man-of-wars to make a living, it also exposes them to constant bombardment by ultraviolet (UV) radiation, says Dunn.
“There are very few other animals that deal with that kind of UV exposure.”
High doses of UV radiation can result in damaged DNA, which in turn leads to mutated cells or cancer, the evolutionary biologist says.
But Portuguese man-of-wars are somehow able to avoid that fate. Dunn speculates that their brilliant colors may act as a kind of sunscreen, with their blue, violet, and purple pigments absorbing different wavelengths of UV light.

Unknowable Beauty

How man-of-wars tolerate high UV exposure is just one of many things researchers don’t know about them, says Dunn.
Their life span is another.
Their gelatinous consistency and open-ocean lifestyle make it especially difficult to study the creatures, Dunn says.
“You can tag a lion and follow it, but you can’t do that with Portuguese man-of-wars.”
And man-of-wars don’t do well in captivity. Researchers can keep them for a limited time but haven’t yet been able to raise them throughout their entire life cycle in the lab, Dunn says.

Deadly Intrigue

“They’re incredibly beautiful animals,” says Dunn.
The evolutionary biologist compares them to artwork created by renowned glass sculptor Dale Chihuly.
That beauty continues to captivate Ansarov, who plans to keep photographing the man-of-wars that wash up on his local beach.
In an age when everyone is constantly bombarded with visuals, it’s easy to take a quick look at an image and move on, he says.
“In nature, it’s become a bad thing because we see a living creature and we consume it visually and move on,” Ansarov says.
“[We] forget the fact that this is a living creature that’s struggling to survive.”
He hopes his images of Portuguese man-of-wars will help people cultivate an appreciation, or at least an understanding, of one of the ocean’s more intriguing animals.

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