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In Gabon, known for its geological diversity and wildlife, scientists were surprised to discover orange crocodiles unique in the world, living in the midst of bat droppings in the world. caves.
"When I approached with my flashlight in the cave, I saw red eyes … crocodile in 2008. Two years later, we released a first specimen of the cave and we realized that it was orange ", remember the geoarchaeologist (archaeological sediment specialist) Richard Oslisly
An extraordinary double discovery that occurred while he and a team of investigators were trying to find remains of human presence in the caves of Abanda, in southern Gabon.
The "Orange Caves Crocodile", which can measure up to 1m70, is unique in the world and has only been seen in the caves of the African country, according to Oslisly.
"At first we thought that the color could be due to its diet, since we have verified that these reptiles eat bats orange," says the French researcher.
But after more detailed studies, the scientists presented other hypotheses: a "depigmentation" caused by the lack of light in these caves or the harmfulness of "guano", a substance composed of bats' droppings. mice in which these animals move in all their underground life.
"The urine of bats began to attack their skin and transform their color," says Olivier Testa, spelunker and member of the scientific team.
Oslisly, Testa and American researcher Matthew Shirley have been increasing scientific expeditions since 2010 to better understand these crocodiles.
When mapping the caves, they found four orange crocodiles on about 40 specimens of this "caveman" species.
Dozens of crocodiles with "normal" pigmentation live in neighboring caves connected to the surface, says Testa, while orange specimens live in caves accessible only by vertical wells.
– A Presence of 3,000 Years –
"We believe that dozens of crocodiles were installed in the caves of Abanda 3000 years ago, which corresponds quite well to a period when the level of the sea had fallen and in which this coastal area was again terrestrial, "says Shirley.
The orange crocodiles were probably trapped in the cave "after entering the hallways when they were little" and not being able to get out of there by growing up, according to Oslisly.
Several more or less narrow and interconnected corridors form a network of caves in Abanda and are sometimes inundated by the rising waters of the water table.
Shirley argues, however, that crocodiles may have been installed in their cave by their own decision and that they can not be trapped there.
In total darkness, these animals survive with a particular diet. In the caves there are no fish or shellfish, and they feed on bats, grbadhoppers and crickets. "It's a particularly demanding environment," says Shirley.
According to the researchers, these specimens, both orange and those of normal color, belong to the group of dwarf crocodiles "Osteolaemus tetraspis" and are "mutating".
The DNA of these specimens is not sufficiently different from the surface of their dwarf cousin to make a new species, says Shirley, but these animals have developed their own "genetic signature".
Cave crocodiles have, in effect, a unique group of genes pbaded down from generation to generation, scientists have found by comparing blood samples of troglodyte dwelling specimens with those of their living dwarf cousins only on the surface in Gabon
Although the crocodile is already a protected species in Gabon, Oslisly advocates that the caves of Abanda become a "fully protected sanctuary".
"There is still much to discover in the caves of Abanda", says the geoarchaeologist, who hopes to promote "scientific tourism".
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