(Photo courtesy of the Galápagos Conservancy)
Scientists were shocked in 2019 when a unique female tortoise was discovered on the volcanic island of Fernandina in the western Galápagos archipelago.
That’s because the last time a Chelonoidis phantasticus, or “fantastic giant tortoise,” was found was in 1906.
“Everything that we knew about this species said it was extinct,” Stephen Gaughran, a postdoctoral research fellow in ecology and evolutionary biology at Princeton University, told The Guardian.
“It was almost too good to be true that there was a tortoise living on Fernandina,” Evelyn Jensen, lecturer in molecular ecology at Newcastle University in the United Kingdom, told CNN. “We were all just so excited.”
When the tortoise, named “Fernanda” after the island where she was found, was compared with the deceased male specimen, which is kept in a museum collection at the California Academy of Sciences, scientists thought they had a problem. That’s because Fernanda doesn’t look like the male.
But by sequencing the genomes of both Fernanda and the museum specimen, and by also comparing them to the other 13 species of Galápagos giant tortoises, Gaughran was able to determine that the two known tortoises from Fernandina are indeed members of the same species.
Gaughran is the co-author of a paper in the current issue of Communications Biology confirming Fernanda’s species’ continued existence.
“Like many people, my initial suspicion was that this was not a native tortoise of Fernandina Island,” Gaughran said in a statement. “We saw — honestly, to my surprise — that Fernanda was very similar to the one that they found on that island more than 100 years ago, and both of those were very different from all of the other islands’ tortoises.”
How Tortoises Got To The Galápagos Islands
Tortoises aren’t native to the Galápagos Islands, and they can’t swim, either. They do, however, float.
Scientists believe that sometime between 2 million and 3 million years ago, an enormous storm carried giant tortoises from South America to the Galápagos. The tortoises then bred with each other on the islands where they landed, resulting in rapid evolution. This interbreeding resulted in the 14 species.
The biggest difference in these tortoises is their shell shape. Some of the tortoises have a domed upper shell. Others, such as the male specimen from Fernandina, have a saddleback-style shell that arches up above the tortoise’s head and neck.
“The arch in the shell gives these tortoises much greater range of motion with their necks, allowing them to reach up higher to eat vegetation up off the ground, so it may have evolved to gain access to more food,” said Jensen, who is co-author of the paper in Communications Biology, according to CNN.
Why Fernanda Is Different
The male tortoise found in 1906 had a shell with an extreme saddleback shape and distinctive flaring around the edges, which is why it was dubbed “phantasticus,” Jensen continued.
On the other hand, Fernanda, who is believed to be more than 50 years old, has a smaller, smoother shell than the 1906 male. That said, she also is smaller in size, which scientists hypothesize may be due to the limited amount of vegetation on the island. Her stunted growth may also have contributed to her shell’s distorted shape.
Are There Others Like Fernanda?
The question on scientists’ minds is now this: Are there other tortoises like Fernanda on the island of Fernandina?
That’s difficult to answer.
The island remains largely unexplored because extensive lava fields block access to its interior. However, purported tortoise droppings have been spotted by aircraft as recently as 2014.
“Fernandina is the highest of the Galápagos islands, geologically young, and is mainly a huge pile of jagged blocks of brown lava,” explained Peter Grant, Princeton Class of 1877 professor of zoology, emeritus, and an emeritus professor of ecology and evolutionary biology at Princeton University. “At lower elevations, the vegetation occurs in island-like clumps in a sea of recently congealed lava. Fernanda was found in one of these, and there is evidence that a few relatives may exist in others.”
As for Fernanda, she now lives in Galapagos National Park’s Fausto Llerena Giant Tortoise Breeding Center, which is a rescue and breeding facility. If more tortoises such as Fernanda are found, conservationists could begin a captive breeding program to keep the species alive.
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