Animal oddities: when nature goes awry, the results are disturbing, wondrous, and - for scientists - puzzling.

When nature goes awry, the results are disturbing, wondrous, and--for scientists--puzzling.

When Jim McMillan, an Iowa veterinarian (animal doctor), reached deep inside a cow to deliver a calf last April, he got more than he bargained for. "I felt two different noses, and thought it was twins," he says. "But then I felt only one set of feet, and went back to the head. I thought, this feels unusual." McMillan can say that again.

The Holstein calf, named Reflections, was born with two heads, four eyes, and three ears. It probably contained one brain, since when the calf licked, its two tongues moved at the same time. "This the type of thing you might see once in a lifetime," McMillan says. Reflections lived for three short days and died, probably of pneumonia.

Reflections is now refrigerated and soon to be stuffed. Could the calf's fate be that of a traveling exhibit? After all, its startling weirdness might intrigue, baffle, or repel you enough to come rake a look.

Farmer Gary Slife treated the calf like an exceptional child, feeding its two mouths with a tube of colostrum --the mother cow's precious disease-fighting milk. Saddened by the calf's brief bout with life, Slife says, "She had two-and-a-half strikes against her when she was born."

What are we to make of the bizarre, disturbing marvel of a two-headed calf? For scientists, the sheer fact of its existence becomes a profound question: Why do such animal defects happen in the first place?

STRANGE DEVELOPMENT?

No one knows how many kinds of animals like Reflections survive, or exactly why they are born--a number of possibilities abound. "Most are simply nature's random mistakes," says Linda Ambrosio, an Iowa State University biologist. In the case of Reflections--and other two-headed animals--Ambrosio speculates the defect starts soon after a fertilized egg begins to develop in the uterus, the organ where fetuses grow during pregnancy.

If, for example, a single egg splits completely in half, each half evolves into a separate baby. Outcome: identical twins. But sometimes the egg doesn't split totally, and twins stay conjoined or physically connected, sharing body parts (see SW 10/4/96).

Conjoined twins are not the result of defective genes, chemical instructions in cells gone awry, Ambrosio says. "It's not a genetic factor. Rather, conjoined twins are the effect of a developmental factor--what happens to an egg forming in the uterus." If Reflections had lived to father calves, his children would have been normal.

Survival for most conjoined twins is a big if They suffer from deformed organs, heart or lung ailments, and are vulnerable to a host of diseases. But if Reflections had made it, he might well have been as huge a celeb as Rudy, a thriving two-headed Yorkshire-Red Duroc pig born in Iowa in August '97.

Rudy sports an oversized head with two snouts and a third, nonworking eye. Aside from an awkward gait and nervous-system problems, he seems to be a typical little piggy. Some might envy Rudy's illustrious fate--he resides in Hollywood and soon plans to make his TV debut. Oddities do pay off sometimes!

ALBINO GATORS

Antoine Blanc, Hannan, and Shulte are celebrities in their own right, drawing crowds of gawkers. They're pure white alligators with bright sky-blue eyes, and they hold court at New Orleans' Audubon Zoo. In this case, gator genes are definitely the cause of theft allure. The alligators are leucistic, which means they have pigmented or colored eyes, but no pigment in theft skin (white tigers are also leucistic). Leucism is a rare form of albinism--most albino animals usually boast white skin and pinkish-yellow eyes.

"The gators are a genetic mutation of the American alligator," says Kathy Landry, Audubon zookeeper. Buried in the cells of every newborn animal is a unique set of genes. The blueprint shapes how the animal will develop and grow, what its eyes, scales, fur, or feathers will be like. But sometimes the instructions have defects.

The gators inherited a defective gene that produces too little melanin, the pigment that lends skin its hue. Their parents may have had normal greenish skin and eyes (no one knows, since the gators were found in the wild). But if an animal offspring is leucistic or albino, then both parents carried the gene for that trait.

Most animals, such as white horses, chickens, and geese are really partial albinos--you can see pigment coloring in their beaks, legs, and eyes. True or complete human albinos (about 1 in 17,000 people) feature milk-white skin and hair, and sometimes pink eyes. (Tiny visible blood vessels in the iris, the eye's colored part, make eyes look pink; the iris hides pinkness in normal eyes.)

Don't look for many albino animals in the wild--their whiteness spells no natural protection against sunlight, and makes albinos too visible for hungry predators. After all, defense against sun and predators are major factors why skin evolved color in the first place.

How does skin get its color? A substance called tyrosinase (ty-RO-sin-ase) is a protein, a building block of living material, which helps skin cells manufacture melanin. A genetic defect in tyrosinase leads to some severe albininsm. Recently developed blood tests can use the substance to identify potential human albino-gene carriers. But as far as Antoine Blanc and his gator pals go, their color--or lack of it--has made them outrageously popular.

FROGS UNDER SIEGE

Frogs with missing, multiple, or twisted legs? Scientists have started to hotly argue the environment's role in the case of the "freaky frogs" (see SW 11/15/96). They made headlines in 1995 when a middle-school class discovered them in a Minnesota pond. And they turned scientists already alarmed at shrinking frog populations into sleuths. What forces were at work?

Biologists consider frogs, toads, and other amphibians "environmental sponges." Their unshelled eggs are easily exposed to chemical pollutants in water; their thin moist skin is susceptible to the harmful effects of polluted air and acid rain (rain made acidic by pollution).

Some researchers think harmful chemicals may be a clue to freaky frogs. Unleashed in water by broken-down plastics and pesticides, the chemicals may damage frog eggs. Some point to the thinning ozone, or atmosphere's protective layer, which lets more ultraviolet light reach frog ponds. Excessive UV light could also trigger damaged eggs.

Another freaky frog expert boasts three radically different theories! At first, developmental biologist Stanley Sessions, at Hartwick College in Oneonta, New York, thought tiny parasites called flukes might be the culprit. "Fluke larva sit in the mud searching for a host," says Sessions. "If an unfortunate tadpole happens to land, they hone in on it, punch a hole in its skin, and squeeze in." The process takes 30 seconds, but a fluke burrowed in a tadpole's limb bud can cause an extra leg to sprout. Scientists don't know exactly why.

But flukes don't account for Minnesota frogs with missing legs. After examining limbless frogs, Sessions cited a second villain: predators like herons or egrets might have ripped off the legs. No way, say critics: Birds dine on, but don't mutilate prey, explains University of Minnesota ecologist Lucinda Johnson. Now Sessions is on his third theory--tadpoles themselves may be the culprit! When they become overcrowded or face short food supply, they nibble on each other.

Whatever the causes, malformed frogs are still baffling scientists. If the environment is behind the precarious state of froggy health, some scientists wonder if human development will one day be affected. No, they may not have answers yet to the complex tangle of animal oddities. But like most of us, scientists regard them as part of nature's awesome round of surprises.