Pictures: Millions of Puppy Mummies in Egypt Labyrinth

As part of the first full excavation ofEgypt's ancient Dog Catacombs, scientists examine 2,500-year-old animal remains—a small sample of the roughly eight million animal mummies in these tunnels.

Likely supplied by ancient puppy mills, most of the mummies are dogs, and many were just hours old when taken for mummification, according to new research based on the summer 2010 excavation.

Snaking beneath the desert at the ancient royal burial ground ofSaqqara (map), the Dog Catacombs were discovered more than a century ago. But only now is research shedding light on the massive number of mummies found in this complex of tunnels and chambers dedicated toAnubis (picture)—jackal-headed god of the afterlife.

Poorly mummified and piled high, the carcasses long ago deteriorated into indistinct heaps, experts say.

"It's not easy to identify individual mummies in the galleries or in the photographs,"saidPaul Nicholsonof Cardiff University in the U.K."We have piles of mummy remains just over a meter {three feet} high, on average, that just fill the side tunnels.

"Although the mummies are not well preserved or well decorated, unlike some museum specimens, they can still give us a great deal of scientific information,"Nicholson added.

The mummies were stacked between about the late sixth century B.C. and the late first century B.C., Nicholson said.

(Related:"Dog Mummies Found in Ancient Peru Pet Cemetery.")

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Pictures: Sharks Taught to Hunt Alien Lionfish

Seemingly striking a blow for ecological balance, a Caribbean reef shark chomps on an invasivelionfishin the clear waters ofRoatan Marine Parkoff the coast ofHonduras.

Working with park officials, local divers are attempting to give sharks a taste for the alien reef species, which are native to the Pacific and Indian Oceans. With no natural predators, lionfish populations have exploded throughout the waters of the Caribbean and U.S. Southeast since their accidental introduction by aquarium hobbyists a decade ago.

In Honduras"local dive masters familiar with the sharks decided to try to turn them on to eating invasive lionfish,"said photographerAntonio Busiello, who recently snapped images of the efforts during three months of diving on the site.

"If these predators start to see lionfish as prey, eventually, in time the lionfish may be kept under control as a part of the ecosystem. That was the idea."

—Brian Handwerk

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Pictures: Trees Cocooned in Spider Webs After Flood

Trees shrouded in ghostly cocoons line the edges of a submerged farm field in thePakistanivillage of Sindh, where 2010's massivefloodsdrove millions of spiders into the trees to spin their webs.

Beginning last July, unprecedented monsoons dropped nearly ten years' worth of rainfall on Pakistan in one week, swelling the country's rivers. The water was slow to recede, creating vast pools of stagnant water across the countryside. (See pictures of the Pakistan flood.)

"It was a very slow-motion kind of disaster,"said Russell Watkins, a multimedia editor with the U.K.'sDepartment for International Development(DFID), the organization tasked with managing Britain's overseas aid programs.

According to Watkins, who photographed the trees during a trip to Pakistan last December, people in Sindh said they'd never seen this phenomenon before the flooding.

(Seepictures:"World's Biggest, Strongest Spider Webs Found.")

—Ker Than

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Photos: Dams Threaten Mekong River Megafishes

This gallery is part of aspecial news series on global water issues.

Thegiant freshwater Mekong River stingrayis just one of many megafish species that could be threatened by ambitious dam-building plans in the Mekong River Basin.

(Read the full story.)

The outcome of a meeting last week among four Southeast Asian countries could determine whether construction of the first of 11 controversial dams on the Mekong River can proceed.

The dams are designed to generate electricity for the region, but environmentalists fear they will disrupt the Mekong's delicate freshwater ecology, which supports dozens of other critical species, and that they will threaten local communities who rely on the river for food and jobs.

This giant fish, found near the Cambodia-Vietnam border in 2002 by National Geographic Emerging ExplorerZeb Hogan, measured 162 inches (413 centimeters) from nose to tail.

(Read more in“GIANT STINGRAY PICTURE: Largest Freshwater Fish?” andwatch video of this enormous species.)

—Tasha Eichenseher and Ker Than

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April Fools'Day Pictures: Six Animal Hoaxes

A woman examines"A Young Family,"a sculpture of a human-like pig and her offspring by Australian artistPatricia Piccinini, at the 50th Venice Biennale of Art in June 2003.

Photographs of the sculpture circulated on the Internet in years afterward with messages suggesting—among other things—that the pictures depicted a human-dog hybrid created by an experiment gone wrong, according to the rumor-squashing websiteSnopes.com.

The human-dog hybrid is one of many animal hoaxes perpetrated over the centuries—especially asApril Fools' Daypranks.

As it turns out, there's actually some human in the sculpture—Piccinini used human hair along with silicone, acrylic, leather, and timber as materials for the artwork, according to her website.

In real life,scientists have already been blurring the line between human and animal by producing chimeras—hybrid creatures that are part human, part animal, National Geographic News reported in 2005. For instance, scientists at the Shanghai Second Medical University in 2003 fused human cells with rabbit eggs—reportedly the first human-animal chimeras successfully created.

(Also see:"April Fools' Day Pictures: Four Historic Science Hoaxes.")

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Radiation in Japan Seas: Risk of Animal Death, Mutation?

If radioactive material from the Fukushima Daiichi nuclear power plant—disabled by the March11Japan earthquake and tsunami—continues to enter theocean, marine life could be threatened, experts say.

(See relatedphotos:"Japan Tsunami: 20 Unforgettable Pictures.")

In the past week, seawater samples taken near the nuclear power plant, onJapan's eastern coast, have shown elevated levels of radioactive isotopes, including cesium 137 and iodine 131, according to theNew York Times.(See"Japan Tries to Avert Nuclear Disaster.")

All life on Earth and in the oceans lives with exposure to natural levels of ionizing radiation—high-frequency radiation with enough energy to change DNA. Most such genetic damage heals, but the addition of human-made radiation can make it harder for the body to repair broken genes.

Radiation concentrations in the Japanese seawater samples have fluctuated in past days, but on Wednesday the amount of iodine spiked to 3,355 times the legal limit for seawater, Japanese nuclear safety officials told the Associated Press.

That level is the highest so far—and an indication that more radiation is entering the ocean, though how is still unknown, the agency reported. Cesium was also found to be 20 times its safety limit on March 28, according to theTimes.

Radiation Can Cause"Bizarre Mutations"

Once in seawater, radiation can hurt ocean animals in several ways—by killing them outright, creating"bizarre mutations"in their offspring, or passing radioactive material up the food chain, according toJoseph Rachlin, director of Lehman College's Laboratory for Marine and Estuarine Research in New York City.

"There will be a potential for a certain amount of lethality of living organisms, but that's less of a concern than the possible effects on the genetics of the animals that become exposed,"Rachlin said.

"That's the main problem as I see it with radiation—altering the genetics of the animal and interfering with reproduction."

Even so, according to radioecologistF. Ward Whicker, the concentrations of iodine and cesium levels"would have to be orders of magnitude larger than the numbers I've seen to date to cause the kind of radiation doses to marine life that would cause mortality or reductions in reproductive potential.

"I am very doubtful that direct effects of radioactivity from the damaged reactors on marine life over a large area off the coast of Japan will be observed,"Whicker, professor emeritus at Colorado State University, said via email.

Likewise, using legal limits to gauge damage to marine life is of little value right now, he said.

To make a"credible assessment"of the risk to marine animals, scientists would have to know the actual concentrations of radioactive iodine in the water and fish or other marine animals off Fukushima Daiichi, he said.

Radiation Hardest on the Little Ones

It's possible that levels of radioactive contamination near the Fukushima nuclear reactors could increase and cause some harm to local marine life, Whicker said.

"If this happens, the most likely effects would be reductions in reproductive potential of local fishes. ... ,"he said.

Marine organisms' eggs and larvae are highly sensitive to radiation, since radioactive atoms can replace other atoms in their bodies, resulting in radiation exposure that could alter their DNA, Whicker said. (Get the basics on genetics.)

Most such deformed organisms don't survive, but some can pass abnormalities on to the next generation, Lehman College's Rachlin said. Either way, the radiation exposure could hurt the population's ability to survive long-term.

Rachlin thinks the most susceptible critters would be soft-bodiedinvertebratessuch as jellyfish, sea anemones, and marine worms—which can take up the radiation more quickly than shelled creatures—though Whicker said fish may be most at risk.

Whicker added,"I would expect any temporary losses in reproduction in local fish to be offset by immigration of unaffected individuals from surrounding areas that would be impacted to a lesser degree."

(See"Chernobyl Birds' Defects Link Radiation, Not Stress, to Human Ailments.")

In addition to its threats to reproduction, pockets of radioactive material can can burn fish passing through, hitting them like a stream of searing water, Rachlin said.

Complicating matters is the fact that predator species in the Pacific such as tuna and sailfish are already stressed byoverfishing, according to Rachlin.

"I'm concerned—this is the spawning season. ... If this impacts the survivorship of the young and larvae, this will be a further insult."

Radiation Threat Here to Stay?

According to chemical oceanographerBill Burnett,"In the short run {the radiation} could have some definite negative impacts"on marine life.

"The good news is the half life {of iodine} is only eight days,"added Burnett, an expert in environmental radioactivity at Florida State University.

So"if they stop the source of radioactive leakage, this is going to be a short-term problem."

However Fukushima Daiichi's leaking cesium is potentially more serious, since that isotope takes 30 years to decay, Burnett said.

Radiation Can Travel Up the Food Chain

There could also be some movement of radiation up the food chain if animals eat irradiated plants and smaller, radioactive animals, Rachlin said.

In particular, plants such askelpcan quickly absorb iodine, FSU's Burnett said. (See pictures of ocean wildlife.)

There's a possibility that the devastation of towns in northeastern Japan caused by the earthquake and tsunami also released toxic metals such as lead into the soil and water, according to Texas Tech University ecotoxicologistRon Kendall.

Previous studies have shown that metals can work in concert with radiation to suppress immune systems in vertebrates, making them more vulnerable to disease, Kendall said.

It's a"big issue for the environment and human health because of the widespread destruction. It takes me back to New Orleans after Hurricane Katrina—this to me is even more complicated with the radiation."

(Seephotos:"Japan Reactor Crisis: Satellite Pictures Reveal Damage.")

Ocean Resilient Against Radiation

The ocean has a"tremendous capacity"for diluting radiation, Colorado State's Whicker noted.

"It also has resilience, in the sense that the area would recover over time as the situation improves and as the radioactivity decays and disperses."

"But I should caution that we have not had much opportunity to study the effects of very large releases of radioactivity into marine ecosystems,"he said. The best data comes from nuclear weapons tests in the Pacific in the 1950s and 1960s.

Texas Tech's Kendall also pointed out that there's not much known about radiation in seawater.

"The dose makes the poison,"he said,"and the more concentrated the radiation, the more potential effects. It's something we definitely need to monitor."

Added Lehman's Rachlin:"If it's a one-shot pulse, OK, not a problem.

But if the radiation leaks continue for several months, Japan may be dealing with a more serious blow to marine life, he said.

The coastline, after all, isn't Chernobyl, he said."We can't cement {over} that whole area."

National Geographic News

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"Castrated" Spiders Are Better Fighters, Study Says

Although emasculated spiders can no longer be lovers, they are better fighters, a new study says.

In many spider species, males have sex using two appendages known as pedipalps. But males will often lose one or both pedipalps during the act—behavior that might seem like a bad idea evolutionarily, since it renders the male sterile.

(Relatedpictures:"'Torture' Phalluses Give Beetles Breeding Boost.")

Scientists have proposed that such genital amputation plugs up a female to help ensure that other males don't successfully impregnate her.

To learn more about why male spiders become eunuchs, scientists examined the mating behaviors of the Southeast Asian orb web spider,Nephilengys malabarensis.(Related:"Largest Web-Spinning Spider Found.")

The scientists found that amputated genitals effectively plugged up a female spider 75 percent of the time. In addition, the team saw that males with missing genitals were far more aggressive and active in guarding females.

During contests between males, full eunuchs that had lost both pedipalps were better fighters than half eunuchs and intact males, the study showed. Overall, the eunuchs were more than three times more likely to attack, chase, and defeat any rivals.

The scientists think that, once a male has lost his means of procreating, he protects his investment further by becoming a superwarrior.

"We think, but are not sure, that the changes in behavior may be due to changing hormone levels"triggered by losing the pedipalps, said study co-author Matjaž Kuntner, a spider expert at theSlovenian Academy of Sciences and Artsin Ljubljana.

"But the ultimate reason for this behavior is that eunuchs, with no reproductive future, have nothing to lose and risk more in contests."

The study also observed that females of this species will frequently devour males after sex, Kuntner added. Males could thus be breaking off their genitals, he said, to help ensure their sperm still has a fighting chance even if they fall victim to cannibalism.

The eunuch-spider study was published online March 23 in the journalAnimal Behaviour.

forNational Geographic News

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