For some scientists, the excitement surrounding the birth of twin panda cubs at the National Zoo last week is just another example of what one researcher calls “panda privilege.” Critics say that zoos lavish resources on pandas, apes, elephants and other “flagship species,” as they’re known, investing less in the millions of other organisms that aren’t impressively large and furry.

It’s a familiar debate among experts on conservation, but the National Zoo has received particularly sharp criticism. Last year, the zoo canceled its its $1 million program for animals without a spine, or invertebrates. Estimates vary, but invertebrates include roughly 99 percent of species. Corals, cuttlefish, leafcutter ants, and other species lost their home when the zoo’s Invertebrate Exhibit closed.

One way or another, many larger animals depend on them for their survival, said Scott Hoffman Black, the executive director of the Xerces Society for Insect Conservation in Portland, Ore.

Take those grizzly bears fishing for salmon on the bear cam in Katmai National Park, Alaska. They’d have nothing to eat if the salmon didn’t have flies to snap at on the surface of a mountain stream.

Or take humans. Our crop yields depend on honeybees and other pollinating insects.

“We, of course, were really disappointed that they decided to move away from educating people about a really important part of biological diversity, which are our insects and other invertebrates,” Black said of the zoo’s decision to close the Invertebrate Exhibit.

Kathleen Buckingham, a researcher at the World Resources Institute in Washington, called it “panda privilege.”

American zoo’s treatment of pandas “raises some wider questions about the hierarchy of the animal kingdom,” said Buckingham, who studied the geopolitics of pandas with colleagues at the University of Oxford. “Invertebrates, nobody will notice if they’re gone, but what’s next to be gone? And what are the implications of that?”

The zoo cited financial considerations in its decision to close the exhibit. The invertebrate program cost $1 million annually to operate and would have required a $5 million renovation to maintain.

There is no media frenzy when a coral clones itself. No one spends hours watching baby cuttlefish emerge from their eggs. And when a colony of leafcutter ants bids farewell to a young queen taking wing on her nuptial flight, no one says anything about her looks.

But when a panda cub is born, she is inevitably the cutest, cuddliest, fluffiest, adorable-est thing any human parent has ever cooed over. When a panda cub dies, it’s front-page news. So critics aren’t surprised that the panda program continues.

The total cost of the panda program is $3.5 million a year, including research, feed, and habitat. About $550,000 is a fee paid to China, which controls the bears.

Only one of the cubs born last week survived, a male. The parents are the zoo’s adult giant pandas, Mei Xiang and Tian Tian.

Away from the zoo, meanwhile, the Smithsonian’s worldwide network of scientists is studying all kinds of species, including invertebrates. A group of researchers is freezing coral sperm from Hawaii, the Caribbean and Australia to preserve the diversity of the animals’ gene pool.

Panda proponents also say protecting just one animal often requires protecting many more. It’s impossible to conserve panda populations with conserving the forests in which they live.

“It’s not as simple as saving a species in a vacuum,” said Steve Monfort, the director of the Smithsonian Conservation Biology Institute in Front Royal, Va. “It’s about the entire system and how it functions.”

He gave bald eagles as an example. Concern about their survival reinforced political support for the federal ban on the pesticide DDT in 1972, but the decision protected countless other birds, too.

Binbin Li, a doctoral candidate in biology at Duke University, said she was drawn to study pandas in part because she realized that pandas had the potential to persuade the Chinese government to dedicate land to conservation, giving other creatures a home as well.

This summer, Li, has been training staff at a Chinese nature reserve to identify individual pandas by their tracks. Her research there, forthcoming in the journal Conservation Biology, catalogs the diversity of species that share a habit with the pandas.

That’s important to Li, who enjoys photographing creatures such as the takin, a relative of the antelope, and the Chinese monal, a colorful pheasant.

“I love pandas,” Li said. “That doesn’t mean I only love pandas.”

Research on other continents suggests that protecting the habitats of flagship species does not always guarantee protection for a broad range of species. One recent study found that parts of South Africa with populations of lions, elephants, leopards, rhinoceroses and buffalo didn’t have large numbers of invertebrates, plants, amphibians and reptiles.

The Xerces Society’s Black agrees with the goal of protecting as many species as possible, backbones or no backbones, and he acknowledged that using more attractive creatures to generate support for conservation is sometimes necessary. Entomologists do the same when they use the monarch butterfly as a poster child for fundraising, he noted.

Yet Black argues that when visitors who come to see a panda cub don’t have a chance to learn about 99 percent of the planet’s animals, the zoo has missed an opportunity.

“A lot of folks who work on invertebrates and insects, it gets exasperating sometimes,” he said. “This is a much broader issue than this one facility.”