Saving the Underworld: Clarifying the subterranean fauna classification for improved conservation

Inevitably, many habitats, including the particularly vulnerable subterranean ones, will continue being erased from our planet as a result of human activities and interests. The challenge is to protect the ones that are the sole habitats to certain organisms, so that their species are safe from extinction. Hence, it is essential that the distribution of every each one of them is clearly defined.

Brazilian scientists Prof. Eleonora Trajano, Universidade Federal de São Carlos, and Prof. Dr. Marcelo Rodrigues de Carvalho, Universidade de São Paulo, discuss the current classification system, its application and complexities in a paper published in the open access Subterranean Biology.

9759_Image 2Nowadays, there are three categories of subterranean fauna accepted. Troglobites live exclusively underground and are usually characterised with reduced or lacking eyes and pale or transparent colors; troglophiles may live both in caves and on the surface, with individuals commuting between these habitats and promoting genetic interchange between subterranean and surface populations; trogloxenes use caves regularly, but must leave them periodically in order to complete their life cycle.

Throughout the years, many alterations and subdivisions have been applied to the classification used when determining whether a cave organism belongs exclusively to the subterranean habitat, or not, before concluding these three groups, also known as the Schiner-Racovitza system. It is important to separate them properly, since the destruction of a habitat to an endemic troglobite, for instance, would immediately wipe out its whole species, as it would be impossible for the animals to move away.

However, many historic publications do not feature enough details about the described species’ distribution, nor identification of the used classification, so that the information is unreliable. Furthermore, there have been times, when people have been even afraid to survey the underground habitats, led by beliefs and associations linking caves to the “World of the Dead”.

In their paper, the authors conclude that the only way to define the species status of subterranean organisms with certainty is to study each species’ dynamics over a period of at least three years, since animals may migrate on a seasonal and/or non-seasonal basis. Also, scientists need to study thoroughly the area outside the surveyed cave, while testing for sampling sufficiency at all times.oo_124566

“When employing classifications of subterranean organisms, especially for conservation purposes, these conditions should be checked for reliability of the status attributed to them,” say the authors. “Misplacing these organisms within the Schiner-Racovitza categories impairs the efficiency of such policies.”


Original source:

Trajano E, Carvalho MR (2017) Towards a biologically meaningful classification of subterranean organisms: a critical analysis of the Schiner-Racovitza system from a historical perspective, difficulties of its application and implications for conservation. Subterranean Biology 22: 1-26.

First description and video of a rainbow boa preying on a vampire bat in a cave in Ecuador

While snakes are well-known enemies to bats, their preying on the winged mammals has hardly been recorded. Furthermore, no bat as big and heavy as the common vampire, has been described being killed and eaten prior to the present study, published in the open access journal Subterranean Biology.

The study, where scientists, led by Sarah Martin-Solano, Universidad de las Fuerzas Armadas, ESPE, Ecuador, record a rainbow boa catching the bat, is the first known such case to have taken place on a cave’s floor. The documented observation serves to confirm that snakes do predate on bats in caves, and is also the first such case known from Ecuador.

Apart from the detailed description, the scientists also provide a film, showing almost in full the event of a rainbow boa catching, killing and swallowing an adult female common vampire bat.

The predation has been observed in a 450-metre-long cave in Tena, Ecuador. There, an adult female common vampire bat, one of the three bat species to feed exclusively on blood, was seen to fly into the cave right over the boa’s head and its waiting open jaws, raised some 30-35 centimetres above the ground.

The approximately 140-centimetre-long snake snatched the bat by the head and immediately brought it down to the floor. Having been strangled by the boa, the bat appeared to give up its resistance about two minutes later, although the predator did not let it go for another seven minutes. Once assured the mammal is dead, the snake started trying different positions from which to fit the bat in its mouth. However, this seemed particularly difficult due to the mammal’s size and the stiffness of its shoulder joints.

Eventually, the rainbow boa began constricting the body once again. Then, starting from the head, the snake managed to swallow the whole bat in 4 minutes and 50 seconds, with the predation measured to last about 25 minutes in total.

In conclusion, the authors suggest that more research needs to be undertaken, so that scientists can find out how common is for snakes to prey on bats in caves.


Original source:

Martin-Solano S, Toulkeridis T, Addison A, Pozo-Rivera WE (2016) Predation of Desmodus rotundus Geoffroy, 1810 (Phyllostomidae, Chiroptera) by Epicrates cenchria (Linnaeus, 1758) (Boidae, Reptilia) in an Ecuadorian Cave. Subterranean Biology 19: 41-50. doi:10.3897/subtbiol.19.8731