Австралийн Хойд нутаг дэвсгэрийн шохойн чулуун агуйгаас шинжлэх ухаанд урьд өмнө бүртгэгдээгүй, биеийн хэмжээгээрээ онцгой том хавч олдсон байна.
Судлаачид Австралийн Карпентарийн буланд орших Пунгалина карстын бүс дэх “Totem Pole” агуйгаас 80 гаруй тунгалаг биетэй хавч илрүүлжээ. “European Journal of Taxonomy” сэтгүүлд нийтлэгдсэн судалгаагаар, эдгээр амьтдыг Megabathynella totemensis хэмээх шинэ төрөл, зүйл болохыг тогтоосон байна. Энэ нь Австралийн агуйгаас олдсон Bathynellacea багийн анхны төлөөлөл болж байгаа юм.
Уг хавчнууд нь зургаан миллиметр орчим урттай бөгөөд энэ бүлгийн амьтдын хувьд “аварга” хэмжээнд тооцогддог. Тэднийг шинэ төрөл гэж ангилах гол үндэслэл нь сарвууны тоо юм; ихэнх төрөл зүйл долоон сарвуутай байдаг бол M. totemensis нь 11 хүртэлх сарвуутай ажээ. Мөн гэрэлгүй, харанхуй орчинд амьдардаг тул биеийн пигментгүй, тунгалаг шинжтэй байна.
Энэхүү нээлт нь Bathynellacea багийн аварга биетэй төлөөлөгчид дэлхийн бүх тивд тархсаныг дахин баталж байна. Өмнө нь Австралийн гүний усны давхаргуудаас ийм төрлийн амьтад олдож байсан ч агуйн системээс илэрсэн анхны тохиолдол нь энэ юм. Судлаачид Австралийн судлагдаагүй агуй болон газар доорх усны системүүдэд олон шинэ зүйл нуугдаж байж болзошгүй гэж үзэж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
More than 80 translucent crustaceans were found swimming in shallow pools inside a limestone cave in Australia’s Northern Territory. Each specimen measured close to six millimetres in length, a size that counts as unusually large within their taxonomic group.
The animals have since been described as a new genus and species, Megabathynella totemensis, in a study published in the European Journal of Taxonomy. It is the first time any species from the crustacean order Bathynellacea has been recorded inside an Australian cave.
The crustaceans were collected from Totem Pole Cave, part of the Pungalina karst area along the Gulf of Carpentaria, where dissolving limestone has carved out caves, sinkholes and underground waterways. Researchers Ana I. Camacho, Kym M. Abrams and Tim Moulds determined the animals could not be placed in any existing genus within the family Parabathynellidae.
The most striking difference was in the number of claws: M. totemensis carries up to 11, while most related species carry only seven.
A New Genus With Nearly Double the Usual Claws
The claw count was distinct enough to justify establishing a new genus rather than simply adding a new species to an existing one. Most related species in the family carry seven claws, while M. totemensis carries up to 11.
Some species in the genus Billibathynella come close, reaching 10 claws, but seven remains the typical number across the family. The difference works out to roughly 57 percent more claws than most relatives carry.
The genus name Megabathynella draws on the Greek word megas, meaning big. The species name totemensis refers to Totem Pole Cave, where the specimens were originally collected.
Bathynellacea is a group of small, blind crustaceans that live in groundwater and cave systems. They are sometimes grouped with other stygofauna because of their dependence on underground water.
Species in this order are typically only a millimetre or two long, so a specimen approaching six millimetres stands out. The study sets its own size thresholds: species over 4 mm are classified as giant, and those between 2.5 and 4 mm as large. At nearly six millimetres, M. totemensis clears the giant threshold by a wide margin.
Physical Traits Suited to a Lightless Cave
The specimens have segmented bodies, protruding teeth and enlarged spines lining the inner wall of the thorax, features visible under close inspection in the lab.
Their translucence is consistent with life in aphotic environments, cave habitats that never receive sunlight. Pigmentation is typically lost across generations in these settings because it serves no purpose in the dark.
The antennules carry more than 12 articles, each fitted with a short, curved, barbed bristle from the fifth segment onward. This is the kind of fine anatomical detail researchers use to tell closely related cave species apart.
Other features set the species apart at an even finer level. The exopod of the thoracopods, the limbs used for swimming and feeding, contains up to 17 articles, each carrying a strong spine at the base of its outer bristle.
A reproductive appendage on the male, known as thoracopod VIII, differs from every previously described form in the family. Despite these distinctions, researchers found M. totemensis most closely resembles other giant cave and groundwater species, including Kampucheabathynella in Asia and Billibathynella and Brevisomabathynella in Australia.
Giant Cave Crustaceans Have Turned Up on Every Continent
The discovery fits a wider pattern researchers have been documenting worldwide. Large and giant Bathynellacea species have now been recorded on every continent, according to the study.
In Australia, earlier discoveries of related giant species came from groundwater aquifers in Western Australia and Queensland, but none had previously turned up inside a cave.
Totem Pole Cave marks the first time this particular combination, a cave habitat paired with a giant-bodied species, has been documented in the country.
Researchers expect the pattern to continue as more of Australia’s caves and aquifers are surveyed. Large sections of the country’s karst systems and groundwater have not yet been examined for microscopic crustacean life.
The study’s authors anticipate that further fieldwork will turn up additional undescribed species, in Australia and in other countries with similar habitats. The more than 80 individuals collected from Totem Pole Cave came from an area that had gone unsurveyed for this kind of fauna, with the researchers noting the animals were essentially “hiding in plain sight.”
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