Sunday, 20 December 2020

Evolution News - Newly-Discovered Centipede is Top Predator in Isolated Cave

Newly-discovered centipede, Cryptops speleorex. Top of the food chain in an isolated Romanian cave.
Photo credit: Mihai Baciu
King of the Cave: New centipede on top of the food chain in the sulphurous-soaked Movile | Pensoft blog

Movile Cave in Romania has been totally isolated from the outside world for 5.5 million years and contains a unique ecosystem entirely dependent on chemosynthetic bacteria, i.e., bacteria that use the minerals in the walls of the cave itself as their source of energy. These bacteria produce a scum on the surface of the underground lake in the cave which forms the basis of the food chain. Their waste products - Sulphur dioxide and carbon dioxide - and the low level of oxygen, makes the atmosphere toxic to creatures such as humans who have not evolved to live in this totally dark, extremely hostile environment.

Here is what I wrote about this cave in 2016:
A centipede (Criptos anomalans) with extra-long antennae.


Photo credit: Patrick Landmann/SPL
The Movile Cave in Constanța near the Bulgarian border was only discovered in 1986 and the extreme difficulty in reaching the inner caves has meant that very few people have actually visited the caves. To date, only about 100 people have been there. Not only is the cave isolated physically from the outside world but it is even sealed by a layer of clay above it which prevents water from the surface percolating down into it. Analysis of the water in the cave shows it to be free from the radioactive caesium and strontium that should be there following the Chernobyl nuclear reactor accident which contaminated the ground-water in the surrounding area. The cave appears to be getting its water from a 25,000 year-old supply from the surrounding spongy sandstone and so this will not be bringing food into the cave. The only ultimate source of energy is the limestone rock itself which is gradually being eroded by the sulphuric acid in the air, so gradually enlarging the cave. The ecosystem is literally eating its own habitat, a process which left to its own devises would inevitably lead to extinction of the life forms in it. If not for an accidental discovery in 1986 we may never have known about these species!

Two woodlice (Armadillium sp.), which lack skin pigment.

Photo credit: Patrick Landmann/SPL
The journey to the inner caves not only involves a long descent by rope but a hazardous underwater journey through a maze of narrow tunnels in complete darkness save only for the light from a helmet lamp. Then when you get there, the atmosphere is toxic, being low in oxygen and high in carbon dioxides and hydrogen sulphide as the waste products of the bacterial chemosynthesis that the system relies on for its energy source, there being no sunlight whatsoever. Specialist bacteria are literally digesting the rocks and forming the mats of bacterial foam on the surface of the acidic water which is the basis of the multicellular organisms' food chain.

Predators such as spiders, centipedes, pseudoscorpions and water scorpions are apex predators and a carnivorous leech lives on earthworms. Spiders still spin webs even though there are no flying insects and only springtails which jump into the air to avoid other predators.

A spider (Lascona christiani)

Photo credit: Patrick Landmann/SPL
Despite its toxic atmosphere (toxic to 'normal' life that is) Movile cave has some 48 different species, 33 of which are believed to be unique. The number and abundance of these different organisms appears to be directly related to the toxicity of the atmosphere for reasons which are not clearly understood. Many of them have no eyes unlike their terrestrial relatives and many are translucent having lost pigments - which have no purpose in complete darkness. Appendages such as antennae and legs tend to be very long because of the need to feel around in the darkness. It is not clear how the ancestors of these creatures got into the cave. Interestingly, one of the spiders seems to be a close relative of one found in the Canary Islands and the evidence suggests a snail may only have been isolated there for about 2 million years. The view is that the isolation of the cave was a result of Africa moving north and coming up against Spain, so closing the Mediterranean off from the Atlantic and causing it to dry out along with the Black Sea to which it is connected via the Bosphorus. Species might have taken refuge in the caves which then became sealed. Another possibility is that they may not all have arrived together but fell in at various times.

Now scientists, Dr Varpu Vahtera (University of Turku, Finland), Prof Pavel Stoev (National Museum of Natural History, Bulgaria) and Dr Nesrine Akkari (Museum of Natural History Vienna, Austria) decided to check the suggestion that the creatures in the cave were merely adapted forms of those widespread on the surface in Europe, based on the morphological similarity between Criptos anomalans and centipedes of the same name found on the surface. To this end they examine a centipedes collected by speleologists Serban Sarbu and Alexandra Maria Hillebrand.

The Pensoft blog post announcing the result of this examination explains:

The scientists exploring the Movile cave (Romania)
“Our results confirmed our doubts and revealed that the Movile centipede is morphologically and genetically different, suggesting that it has been evolving from its closest surface-dwelling relative over the course of millions of years into an entirely new taxon that is better adapted to life in the never-ending darkness,” explain the researchers. “The centipede we described is a venomous predator, by far the largest of the previously described animals from this cave. Thinking of its top rank in this subterranean system, we decided to name the species Cryptops speleorex, which can be translated to the “King of the cave”, they add.

The team's findings were published in the open access journal, ZooKeys:

Abstract

A new species of Cryptops Leach, 1814, C. speleorex sp. nov., is described from Movile Cave, Dobrogea, Romania. The cave is remarkable for its unique ecosystem entirely dependent on methane- and sulfur-oxidising bacteria. Until now, the cave was thought to be inhabited by the epigean species C. anomalans, which is widespread in Europe. Despite its resemblance to C. anomalans, the new species is well-defined morphologically and molecularly based on two mitochondrial (cytochrome c oxidase subunit I COI and 16S rDNA) and one nuclear (28S rDNA) markers. Cryptops speleorex sp. nov. shows a number of troglomorphic traits such as a generally large body and elongated appendages and spiracles, higher number of coxal pores and saw teeth on the tibia of the ultimate leg. With this record, the number of endemic species known from the Movile Cave reaches 35, which ranks it as one of the most species-rich caves in the world.

Introduction

Located in the southeastern part of Romania not far from the Black Sea Coast, Movile Cave is the first known subterranean chemosynthesis-based ecosystem (Sarbu et al. 2019). Being completely isolated from the outside environment for 5.5 million years, the cave is remarkable for its unique ecosystem entirely dependent on methane- and sulfur-oxidising bacteria, which release nutrients through chemosynthesis for fungi and other cave animals along the food chain. This subterranean ecosystem is also notable for being rich in hydrogen sulfide, methane (1–2%), ammonia and CO2 (1.5–3.5%) whereas it is poor in O2 (7–16%). Relative humidity in the cave is 100% and there is no detectable air movement. The cave was first discovered in 1986 and since then, only a handful of people have visited it (Sarbu et al. 2019).

Despite its harsh living conditions, Movile Cave ecosystem is known to harbor a diverse and unique fauna. The cave hosts 51 invertebrate species, of which 34 species are endemic (Sarbu et al. 2019). Among these species, some present a number of unique adaptations to a troglobitic life in caves, such as the troglobiont water scorpion Nepa anophthalma Decu, Gruia, Keffer & Sarbu, 1994 (Hexapoda, Hemiptera, Nepidae); the nesticid and liocranid spiders Kryptonesticus georgescuae Nae, Serban & Weiss, 2018 (Araneae: Nesticidae) and Agraecina cristiani (Georgescu, 1989) (Araneae, Liocranidae); the cave leech Haemopis caeca Manoleli, Klemm & Sarbu, 1998 (Annelida, Hirudinea, Haemopidae) and the isopod Armadillidium tabacarui Gruia, Iavorschi & Sarbu, 1994 (Crustacea, Isopoda, Armadillidiidae) (Sarbu et al. 2019).

Five species of myriapods are hitherto discovered from the innermost parts of Movile viz. Archiboreoiulus serbansarbui Giurginca, Vănoaica, Šustr, & Tajovský, 2020 (Diplopoda), Symphylella silvestri, 1902 sp. (Symphyla), Geophilus alpinus Meinert, 1870 and Clinopodes carinthiacus (Latzel, 1880) (Geophilomorpha) and a troglobitic population of Cryptops anomalans Newport, 1844 (Negrea 1993; Sarbu et al. 2019). It is worth mentioning that the latter taxon has been only studied morphologically (Negrea 1993, 2004).

Recently, we had the occasion to study freshly collected specimens of an undetermined species of the genus Cryptops Leach, 1814 from Movile Cave. Using both, morphological and molecular evidence, the cave specimens were compared with those of C. anomalans living on the surface, outside the cave. A phylogenetic analysis of 29 Cryptops specimens from different parts of Europe, including two from inside Movile Cave, based on two mitochondrial (cytochrome c oxidase subunit I COI and 16S rDNA) and one nuclear (28S rDNA) markers was performed. Morphological and molecular analyses confirmed that the cave specimens from Movile correspond to a new species, Cryptops speleorex sp. nov., that we describe herein. Additionally, we provide an annotated list and a key to the troglobitic Cryptops species in the world.

Vahtera V, Stoev P, Akkari N (2020)
Five million years in the darkness: A new troglomorphic species of Cryptops Leach, 1814 (Chilopoda, Scolopendromorpha) from Movile Cave, Romania.
ZooKeys 1004: 1-26. doi: 10.3897/zookeys.1004.58537

Copyright: © 2020 The authors. Published by Pensoft Publishers.
Open access
Reprinted under a Creative Commons Attribution 4.0 International License (CC BY 4.0)

Not only is this a great example of how species evolve and diverge from the founder population under the influence of the local environment, but it gives me another opportunity to challenge creationists to explain something I challenged them to explain in 2016, only none of them appeared to be able to:

Given that Bible-literalist creationists believe that everything their putative creator created was for the benefit and use of mankind because the Bible says so, how did creating it in a hidden cave with a toxic atmosphere benefit mankind?

The other question this example raises, of course, is how exactly did these creatures get into a cave which has been geologically isolated for 5.5. million years, having survived on the Ark, just a few thousand years ago, on a planet that is under 10,000 years old?

Answers in comments below, please.







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