Габоны Абанда агуйн гүнд амьдардаг африк одой матарнуудын биеийн бүтэц орчин нөхцөлөөсөө шалтгаалан өөрчлөгдөж байгааг судлаачид тогтоожээ.
Габон, Камерун, Нигерийн нутагт тархсан африк одой матарнуудын энэ бүлэг 3000 орчим жилийн өмнөөс агуйд амьдрах болсон байж болзошгүй гэж эрдэмтэд таамаглаж байна. Энэхүү өвөрмөц бүлэг нь харанхуй, багтаа баялаг орчинд амьдрахын тулд агуйн гүн дэх амьтдын ялгадас болон тэнд унасан сарьсан багваахайгаар хооллон дасан зохицжээ. Байгаль хамгаалал судлаач Мэтт Ширлигийн ажигласнаар, агуйд амьдардаг эдгээр амьтдын зарим нь тод улбар шар өнгөтэй болж, арьс нь хэт нимгэрсний улмаас гавлын ясны хэлбэр нь тод харагдах болсон байна.
Судлаачид энэхүү өөрчлөлтийг удаан хугацааны туршид багваахайн ялгадастай харьцсаны үр дагавар хэмээн таамаглаж байна. Багваахайн ялгадас нь улирлын нөхцөл байдлаас хамааран хүчиллэг чанар нь өөрчлөгддөг тул идэмхий бодисын нөлөөгөөр матруудын арьс гэмтсэн байж болзошгүй гэж үзжээ. Энэхүү таамаглал нь хараахан батлагдаагүй бөгөөд зөвхөн агуйд удаан хугацаагаар амьдарсан, ялангуяа биеэр том, настай эр матарнуудад илүү тод ажиглагдаж байгаа юм.
Судалгааны явцад эрдэмтэд агуйн харанхуй, хүнд нөхцөлд амьдардаг эдгээр амьтдын зан төлөв болон физиологийн өөрчлөлтийг нарийвчлан судалж байна. Матруудын арьс нимгэрч, яс нь ил гарч байгаа нь химийн болон физикийн нөлөөлөлтэй холбоотой байж болох ч яг тодорхой шалтгаан нь одоогоор тодорхойгүй хэвээр байна. Абанда агуйн энэхүү экосистем нь дэлхийд ховор тохиолдох амьтдын дасан зохицлын жишээ болж байгаа юм.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
Deep inside Gabon’s Abanda Caves, some of the world’s smallest crocodiles are living a very strange life. They spend years in darkness, surrounded by bats and piles of guano, and some older males have even turned bright orange, with skin so thin that parts of their skull can be seen underneath.
The animals appear in National Geographic’s new series AFRICA: Earth’s Wild Home, which looks at unusual wildlife and rarely seen animal behavior across the continent. Among all the species featured, these cave-dwelling crocodiles are easily one of the strangest.
African dwarf crocodiles are found in Gabon, parts of Cameroon and Nigeria, but the Gabon population has done something no other known crocodile population has been documented doing: it moved into caves. The source says this shift may have started around 3,000 years ago, giving the animals plenty of time to get used to a world with almost no light.
The Caves Are Harsh, But They Are Full Of Food
At first glance, a hot cave full of bat droppings does not sound like a great place to live. For these crocodiles, it comes with a few advantages.
The caves offer shelter and water, and the bats provide a surprisingly useful food source. Every day, huge numbers of bats fly in and out of the cave system. In the confusion, some fall to the ground. That is where the crocodiles come in.
Conservation ecologist Matt Shirley, who worked as a consultant on the series, explained that the bats sometimes become tangled during these crowded flights and end up within reach of the crocodiles below.
Getting close to the animals is not exactly easy. Shirley said his first trip into the cave went badly when around 10,000 disturbed bats flew into his face and body. Going in at night turned out to be a better option, since many of the bats had already left.
The crocodiles themselves were much less intimidating. Shirley described some of the smaller ones as curious, even running up to him with wagging tails to see what was happening.
Why Are Some Of Them Bright Orange?
The orange color was not obvious at first because the crocodiles were covered in guano. Once researchers handled them, they realized some of the animals were bright orange underneath. The exact reason is still unknown, but Shirley believes long-term exposure to bat waste is the most likely explanation.
“These animals have been in these cave systems for 10, 20, 30 years or more, and literally just sitting in bat guano the entire time,” he told IFLScience.
Bat guano can change in pH depending on the rainy season, drier periods and the size of the colony. Shirley described it as a highly caustic material.
That may explain why the orange color appears mostly in larger, older males. They could simply have spent much longer exposed to the cave environment. The explanation has not been confirmed. Shirley stressed that it is still a hypothesis.
Their Skull Is Becoming Visible
Shirley also noted that the skin on the head of some crocodiles has become so worn down that the shape of the skeleton underneath is visible.
“If you look at the head, some of the skin has eroded so thin you can actually see the skeletal features underneath it,” he said.
He thinks the process may be physical or chemical, caused by years of contact with the cave environment and bat guano. The first orange crocodile caught researchers completely off guard. Shirley remembered looking at it and thinking.
“Holy cow, what have we been looking at?” But these orange cave crocodiles stand out for one simple reason: almost everything about their life underground is unusual.
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