What's up in Oddtober?

This leucistic American alligator can be seen in the River Journey building at the Tennessee Aquarium. Unlike albinoism, which is characterized by reduced pigment in the body, leucism results from defects in pigment cells, causing a lack of natural color in all or part of the body.

A ghostly baby alligator, a fish that breathes air, another that catches birds and a stealthy, tentacled squid are among the "wonderfully weird" creatures to discover this month, nicknamed Oddtober, at the Tennessee Aquarium.

"This is a great time to celebrate animals that are somewhat bizarre or that display really cool behaviors," says Thom Demas, curator of fishes.

"Right now, we are one of the only places where you can see bigfin reef squid up close," he says. "These guys not only look like aliens, they lead pretty amazing lives."

Their "big fins" run the length of their bodies, undulating to move with stealthy precision while stalking prey. If their eight arms and two tentacles don't send a shiver down your spine, the way they peer at you will, Demas says. "They have huge eyes, which when compared to their body size, are the largest in the animal kingdom."

Like their bizarre cousins the cuttlefish, also on view, bigfin reef squid have the ability to change the color of their skin using special cells called chromatophores.

Another chilling species is the African tigerfish, a recent addition to the aquarium's Lake Tanganyika exhibit. This top predator often can be seen patrolling the middle of the tank, its razor-sharp teeth easily on view.

"The tigerfish earns its name," says Brad Thompson, one of the aquarium's fish experts. "These fish have been known to stalk birds in flight from just below the surface. As the birds skim the surface to catch insects, the tigerfish leaps out of the water to eat them. It's truly incredible behavior. The tigerfish is the only species of freshwater fish that I know of that has been documented catching birds in flight."

Then there's the Southern American lungfish. When the waters of the Amazon River recede during the dry season each year, this species deals with the drought by digging in.

"It sounds weird, but lungfish are obligate air breathers," says fish expert Elaine Robinson. "They can actually drown if denied access to the surface. So when their water source dries up, they burrow into the mud secreting a special mucous that keeps their skin from drying out."

Since they normally breathe air, these "fish out of water" can spend months underground until the next rainy season replenishes their river system, she says.

Visitors also will find a new creature that's missing most of its natural coloration. A ghostly white baby American alligator can be seen in the River Journey building. This animal, along with a few siblings, was recovered by the U.S. Fish and Wildlife Service last spring.

"The occurrence of white alligators, both leucistic and albino, is extremely rare," says Dave Collins, curator of forests. "White hatchlings normally only survive a few days in the wild, as their coloration makes them highly susceptible to predation and possible damage from sunlight."

Leucism results from defects in pigment cells, causing a lack of natural color in all or part of the body. Albino animals have reduced pigment throughout their bodies, making their eyes appear red. Visitors will notice that this tiny gator has some pigment and normal eye color. The aquarium also has two leucistic alligator gar among the freshwater species in the River Giants exhibit.

Nearly two dozen Extraordinary Experiences will be offered free with aquarium admission each day to introduce visitors to even more fascinating creatures. A special Oddtober cellphone audio tour will deliver the 4-1-1 about what's O-D-D in many other locations.

Costumed SCUBA divers will make daily appearances, even carving pumpkins underwater each Saturday in October.