Tag: cave

Exploring the hidden treasures of Aziza Cave: A biodiversity hotspot in North Africa

Aziza Cave harbors a rich and diverse array of subterranean life that is only now beginning to be revealed widely.

Guest blog post by Marconi Souza-Silva

Beneath the arid pre-Saharan zone of Morocco lies Aziza Cave, also known as Kef Aziza or Tazouguert Cave. The vast subterranean system stretches over 3.5 kilometers of surveyed galleries, making it Morocco’s fifth-largest cave system and one of the top ten most extensive caves in North Africa.

A view of the Sahara desert and Aziza cave’s entrance.

Beyond its sheer size and geological significance, Aziza Cave harbors a rich and diverse array of subterranean life that is only now beginning to be revealed widely. In a recent study in the journal Subterranean Biology, researchers cataloged the subterranean fauna of Aziza Cave and provided a detailed checklist of 26 different taxa potentially representing cave-restricted species. Among these are 22 troglobitic species, organisms that have adapted to life entirely within the cave environment, and four stygobitic species, which have specially evolved to live in the cave’s groundwater.

The discovery of such a variety of species highlights the cave as a critical biodiversity hotspot, not only in Morocco but for the African continent as a whole. One alarming aspect of this discovery is the large number of species that still need to be thoroughly studied or described.

Only about 34.6% of the species in Aziza Cave have been formally identified and described by scientists. Further research could lead to the identification and description of many new species. The fauna found in Aziza Cave includes a wide variety of life forms, with the richest groups being beetles (Coleoptera), spiders (Araneae), springtails (Entomobryomorpha), and woodlice (Isopoda). Some have evolved remarkable adaptations to their lightless, nutrient-scarce environment, such as reduced pigmentation, elongated appendages, and heightened sensory capabilities that help them navigate and survive in this extreme habitat.

Despite these discoveries, much of Aziza Cave remains unexplored. Large portions of this karstic system have yet to be surveyed, and researchers believe that the biodiversity uncovered so far is just the beginning. The cave’s unexplored depths likely hold many more secrets, including potentially new species that have yet to be seen by human eyes. This prospect has sparked great interest among speleologists and conservationists, who see Aziza Cave as an important research site for studying subterranean ecosystems.

The biodiversity of Aziza Cave is something to celebrate, but it also sheds light on the significant conservation challenges that subterranean habitats in Morocco and across North Africa are facing. Caves are delicate ecosystems that are highly sensitive to changes in their environment. Human activities such as pollution, mining, deforestation, and unsustainable tourism pose severe threats to these ecosystems and the species that depend on them. Once these habitats are damaged or destroyed, it is often impossible to restore them, and the species that inhabit them may face extinction.

Human-induced impacts have already begun to take their toll in Aziza Cave. Visitors can disrupt the delicate balance of the cave’s ecosystem, change water quality, or introduce pollutants and alien species. These pressures underscore the urgent need for conservation measures to protect this unique environment and its inhabitants. By highlighting the importance of Aziza Cave and similar habitats, the researchers hope to encourage further exploration and study of Africa’s subterranean ecosystems and develop effective conservation strategies to protect them. By protecting these fragile ecosystems and supporting scientific exploration, we can ensure that the incredible biodiversity of Aziza Cave and other subterranean habitats continues to thrive.

Research article:

Moutaouakil S, Souza-Silva M, Oliveira LF, Ghamizi M, Ferreira RL (2024) A cave with remarkably high subterranean diversity in Africa and its significance for biodiversity conservation. Subterranean Biology 50: 1-28. https://doi.org/10.3897/subtbiol.50.113919

Dragons out of the dark: 6 new species of Dragon millipedes discovered in Chinese caves

Six new species of Chinese dragon millipedes, including species living exclusively in caves, are described as a result of an international cooperation of research institutes from China, Russia and Germany. These cave species have unusually long legs and antennae, with one of them resembling a stick insect, only with a lot more legs. Others appear ghostly white and semi-transparent. The study is published in the open-access journal ZooKeys.

Underresearched in many tropical countries, numerous millipede species are still awaiting discovery and description in China as well. In the present study, three researchers from South China Agricultural University, the Russian Academy of Sciences, and Zoological Research Museum Alexander Koenig describe six particularly extraordinary new species of so-called ‘dragon millipedes’ from the two southern Chinese regions of Guangdong and Guangxi Zhuang. Both areas host a large number of spectacular caves, which have only recently been thoroughly surveyed. Four of the species never leave their underground homes.

Dragon millipedes, a genus of millipedes living in southeastern Asia, are characterised with their ‘armour’ of unusual spine-like projections. Furthermore, some of these species produce toxic hydrogen cyanide to ward off predators.

Among the public, the genus gained particular attention when the “Shocking pink dragon millipede” was discovered in Thailand in 2007. This discovery highlighted a large number of unknown millipede species in the Mekong region and worldwide. While the newly described cave dragon millipedes from China lack the “shocking” warning colour of their surface-living relatives, they are no less spectacular.

One of the new millipedes has received a formal name translating to the “stick insect dragon millipede” because of its extremely long legs and antennae. Therefore, it looks a lot like a stick insect, only with much more legs. Another two of the species have fully lost their colours, which is a common characteristic among exclusively cave-living animals. As a result, they appear ghostly white and even semi-transparent.

Miss Liu Weixin, PhD candidate at the South China Agricultural University in Guangzhou, China, and co-author of the present study, has conducted the research at the Centre of Taxonomy at the Research Museum Koenig (ZFMK), Leibniz Institute for Animal Biodiversity in Bonn, Germany as a part of her PhD, which focuses on Chinese cave millipedes. She worked along with her advisor and lead author Prof. Tian Mingyi, and renowned millipede expert Dr. Sergei Golovatch from the Russian Academy of Sciences, Moscow.

Over the course of her PhD, Miss Liu Weixin has explored more than 200 Chinese caves, where she has discovered over 20 new millipede species. The dragon millipedes are among her most spectacular discoveries as they exhibit extreme cave adaptations including loss of pigmentation and extremely elongated legs and antennae.

Still on her guest research year in Germany, Liu is currently busy describing additional batch of more than two dozen millipede species, she collected from the Chinese caves, literally bringing to light an unknown world.

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Original source:

Liu WX, Golovatch SI, Tian MY (2016) Six new species of dragon millipedes, genus Desmoxytes Chamberlin, 1923, mostly from caves in China (Diplopoda, Polydesmida, Paradoxosomatidae).ZooKeys 577: 1-24. doi: 10.3897/zookeys.577.7825

Huge organs defy austerity for tiny cave snails in the subterranean realm

While most of the knowledge about tiny snails comes from studying empty shells sifted out from piles of dust and sand, the present research is the first contemporary microscopic exploration of organs in cave snails tinier than 2 mm. The paper, published in the open-access journal Subterranean Biology, reveals that underneath the seemingly fragile shells of the Zospeum genus, there are strikingly huge organs.

A number of remarkable observations such as an enormous kidney, grooved three-pointed teeth and a huge seasonally present penis are reported in the recent study, conducted by Adrienne Jochum, Naturhistorisches Museum der Burgergemeinde Bern, Switzerland, and her international team of researchers from University of Bern, Switzerland; Shinshu University, Japan; Universitaetsklinikum Giessen und Marburg GmbH, Germany; Justus-Liebig University Giessen, Germany; University of Ljubljana, Slovenia; University of Bern Goethe-University Frankfurt, Germany; Ruhr University Bochum, Germany; Croatian Biospeleological Society, Croatia and University Duisburg-Essen, Germany.

The scientists describe these characteristics as adaptations the miniature creatures have acquired in order to survive austerity in the subterranean realm.

Usually, adaptations to cave life can include blindness or lack of eyes, loss of pigmentation, sensitivity to changes in temperature and humidity, a high starvation tolerance, or anatomical compromises such as small size and transparent shells. The present study shows that miniscule carychiid subterranean snails have developed huge organs to tolerate the unique conditions of cave life.

“Studying adaptations in extreme environments such as those found in snails of subterranean habitats can help us to understand mechanisms driving evolution in these unique habitats,” explains the first author.

Glassy cave-dwelling snails known only from Northern Spain, the southern Eastern Alpine Arc and the Dinarides might have tiny hearts, but their enormous kidney extends from one to two thirds of the total length of their minute shells. This phenomenon could be explained as an effective mechanism used to flush out large amounts of excess water during flooding seasons in caves.

The same impressive creatures have also developed elaborate muscular plates, forming the girdle that surrounds the gastric mill (gizzard) in their digestive tract. The muscular gizzard grinds the grainy stew of microorganisms and fungi the snails find in moist cave mud. These mysterious creatures graze stealthily using an elastic ribbon (radula), aligned with seemingly endless rows of three-pointed, centrally-grooved teeth, as they glide through the depths of karst caves while searching for food and partners.

Deprived from the hospitable aspects of life we have grown used to, some of the snails discussed in the present paper have evolved their reproductive system in order to be able to reproduce in the harshest of environments, even when they fail to find a partner for an extended period of time.

As a result, not only are these snails protandric hermaphrodites, meaning that they possess male sexual features initially, which later disappear so that the female phase is present, but they have a large retractable, pinecone-shaped penis for instantaneous mating in the summer when mating is most probable. To guarantee offspring, a round sac, known as the receptaculum seminis, stocks sperm received from a partner during a previous mating and allows them to self-inseminate if necessary.

Teeth in these cave snails are also described using histology for the first time. They bear a median groove on the characteristic cusps known for the Carychiidae.

Sketchy, past dissections provide the current knowledge upon which the findings from this investigation are based. Otherwise, historical descriptions of these tiny snails are only known from empty shells found in samples of cave sediment. The genus Zospeum can only be found alive by inspecting cave walls using a magnifying glass.

“Knowledge of their subterranean ecology as well as a “gut feeling” of where they might be gliding about in their glassy shells is necessary to find them,” comments Adrienne Jochum. The authors also emphasize that this groundbreaking work is important for biodiversity studies, for biogeographical investigations and for conservation management strategies.

Adrienne Jochum and her team investigated the insides of the shells using nanoCT to differentiate species in synchronization with molecular approaches for genetic delimitation. Four well-defined genetic lineages were determined from a total of sixteen Zospeumspecimens found in the type locality region of the most common representative, Zospeum isselianum. This investigation is the first integrative study of live-collected Zospeum cave snails using multiple lines of data (molecular analyses, scanning electron microscopy (SEM), nano-computer tomography (nanoCT), and histology.

This work is dedicated to the industrious Slovenian malacologist Joze Bole, whose work greatly inspired the present research.

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Original source:

Jochum A, Slapnik R, Klussmann-Kolb A, Páll-Gergely B, Kampschulte M, Martels G, Vrabec M, Nesselhauf C, Weigand AM (2015) Groping through the black box of variability: An integrative taxonomic and nomenclatural re-evaluation of Zospeum isselianum Pollonera, 1887 and allied species using new imaging technology (Nano-CT, SEM), conchological, histological and molecular data (Ellobioidea, Carychiidae). Subterranean Biology 16: 123-165. doi: 10.3897/subtbiol.16.5758

Cave snail from South Korea suggests ancient subterranean diversity across Eurasia

As tiny as 1.7 mm, a snail whose relatives live exclusively in the deep recesses of caves, provided a sensational discovery from the depths of Nodong cave, South Korea, back in 2000 for its collector, J. S. Lee. It is the only cave-dwelling representative of the family of hollow-shelled snails in the whole of Asia with its closest relatives known from as far as Croatia and Northern Spain. The scientists, Adrienne Jochum, Bern University and Natural History Museum Bern, Larisa Prozorova and Mariana Sharyiool from the Far Eastern Russian Academy of Sciences and Barna Páll-Gergely from Shinshu University, published its description in the open-access journalZooKeys.

The Asian species has awaited 15 years to come out of the dark for a name and into the limelight of subterranean biodiversity and conservation awareness. This barely visible snail suggests a former pan-Eurasian distribution of cave-dwelling, hollow-spired snails.

The tiny-shelled treasure, called Koreozospeum nodongense, belongs to a larger group of ancient cosmopolitan air-breathing relatives known to have been amongst the first snail colonisers of land via mangroves about 65 million years ago. Similar to its European relatives from the genus Zospeum, the South Korean snail was also found on muddy cave walls.

Although more than 1,000 caves have been explored in South Korea, Nodong is so far the only one to harbour these beautiful denizens of the dark. Hypotheses made by Culver et. al. in 2006 about the existence of a very narrow, mid-latitudinal ridge of subterranean biodiversity (ca. 42-46°N in Europe and 33-35°N in North America) might clarify this unique find.

A high amount of caves known to exist within these latitudes provide ample habitats for colonisation of life. If this hypothetical ridge were to be extended further East away from Europe, then Koreozopseum‘s gliding along walls in a South Korean cave (33-35°N) makes a strong call for further investigations and discovery of rare biodiversity.

Jochum and her international team described K. nodongense using computer tomographic scans (Nano-CT) in a video film to view and compare the contours and architecture of the very fragile shell. Chemical trace elements, such as aluminum (Al) and silicon (Si) were detected in other scans of the thin diaphanous shell using mineralogical analysis techniques (SEM-EDX). These elements may play a role in the biomineralization (hardness) of the shell or may be contaminants absorbed by the snail from sediment consisting of volcanic ash from former eruptions in the region.

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Original Source:

Jochum A, Prozorova L, Sharyi-ool M, Páll-Gergely B (2015) A new member of troglobitic Carychiidae, Koreozospeum nodongense gen. et sp. n. (Gastropoda, Eupulmonata, Ellobioidea) is described from Korea. ZooKeys 517: 39-57. doi: 10.3897/zookeys.517.10154

Additional information:

The Naturhistorisches Museum der Burgergemeinde Bern, Switzerland and the Far Eastern Branch of the Russian Academy of Sciences supported this work.