As American Airlines passengers settle into their flights, they’re probably not thinking about what’s under their seats in the belly of the plane.

Luggage, they might venture. But on any given flight, far more than suitcases is likely to be traveling with them.

Along with the aircraft parts, cellphones, computers and computer chips, medical equipment and medicines — the backbone of trade in South Florida — there is some decidedly more exotic and unusual cargo shipped through Miami International Airport (MIA).

Think live Florida lobsters destined for China, monkeys, blueberries from Chile, gold artifacts, stacks of currency, tissue and blood samples, tropical fish in super-oxygenated water. American has even transported lions, cheetahs and baby sharks in its passenger planes.

Cargo carriers such as Tampa Air Cargo, LAN Cargo, DHL Express and FedEx fly even bigger animals, including manatees, race horses and polo ponies. Hyenas, jaguars, a variety of fish and fowl, Gila monsters and goats also have traveled on all-cargo flights.

And remember that film “Snakes on a Plane”? King cobras — albeit well-secured king cobras — also have been high fliers.

While most live animals are moved around the country by truck or rail, zoos and aquariums, owners of race and show horses and exotic pet dealers often choose air cargo to minimize travel time and reduce the stress on animals — despite the higher cost.

For animals traveling internationally, air cargo is typically the best alternative. And Miami is the second-busiest U.S. airport, after Los Angeles, for transporting live wild animals, according to Sandy Cleva of the U.S. Fish and Wildlife Service’s Office of Law Enforcement at MIA.

“We see wild animals come through as cargo pretty much every day,” said Cleva. “We get reptiles, fish, mammals, birds. Someone imported a hyena as a pet.”

Cleva is part of a team at MIA that includes 10 wildlife inspectors and a wildlife detector dog. They keep busy enforcing federal air cargo regulations on shipping live animals, checking for disease and watching for attempts to import or export endangered species.

“We have to clear the export and import of all animals,” Cleva said.

In the past year, she said, Miami inspectors have seen jaguars that were confiscated in Panama and imported by a U.S. zoo, a black rhinoceros being shipped to a zoo in Mexico, and an Andean condor traveling to Colombia for release to the wild.

The Noah’s Ark of creatures passing through MIA also has included a giant tortoise, golden poison arrow dart frogs, a blue-ringed octopus, sun fish, a hammerhead shark, red-bellied piranha and giant isopods — crustaceans related to shrimp and crabs.

American also does a brisk business in moving pets — sending some 2,200 around the world each month.

But horses, cattle, pigs and goats get to fly, too, thanks to Alex Allesandrini, co-owner of Miami-based Worldwide Livestock Services. “About 80 percent of what we ship are horses, 10 percent pigs and about 10 percent goats, sheep and cows,” he said.

“A lot of polo ponies come in to compete in Wellington [Fla.] from Argentina, Ecuador, Chile and Uruguay. We get a lot of work from the racetracks,” he said.

Worldwide moves about 11,000 horses through Miami every year, Allessandrini said, including jumpers, dressage and eventing horses that spend six months in the U.S. and six months in Europe.

The company also ships zoo animals and exotics. It has its own warehouse and specialized stalls for shipping the animals and uses several carriers — Martinair Cargo, FedEx, DHL Express, Polar Air Cargo, LAN Cargo and Tampa Air Cargo.

Last fall, Plantation, Fla.-based DHL Express was involved in one of the more unusual animal-moving operations in recent years, moving five manatees between Florida and the Midwest. As part of a U.S. Fish and Wildlife Service rescue and rehabilitation program, sick, injured or orphaned manatees recuperate in critical care centers such as Miami Seaquarium, and then, when they are healthy enough, are moved to other participating centers to put on weight.

On Oct. 11, the courier service flew two rehabilitated sea cows (Pixie and Wheezy) that had been living at the Columbus (Ohio) Zoo and Aquarium and another (Woodstock) that had been staying at the Cincinnati Zoo & Botanical Garden to Miami. All three were scheduled to be released into the wild after acclimation at Florida facilities.