Anne IPSEN & Friedhart KNOLLE: The olm of Hermann's Cave, Harz Mountains... / »SOS Proteus« – FIELD NOTE 
Biotehniška fakulteta Univerze v Ljubljani in Nacionalni inštitut za biologijo, Ljubljana, 2017 
51 
The olm of Hermann’s Cave, 
Harz Mountains, Germany – 
eggs laid after more than 80 
years 
 
Močerili iz jame Hermannshöhle v 
Nemčiji po več kot 80 letih odložili jajca 
 
Anne IPSEN1 & Friedhart KNOLLE2 
1Fledermaus-Zentrum GmbH, Oberbergstrasse 27, 
D-23795 Bad Segeberg, Germany; E-mail: 
ipsen@noctalis.de 
2Arbeitsgemeinschaft für Karstkunde Harz e.V., 
Grummetwiese 16, D-38640 Goslar, Germany;  
E-mail: fknolle@t-online.de 
 
Since 1931, live individuals of Proteus anguinus, 
the proteus or olm (Fig. 1), have been kept in an 
artificial environment in the show cave 
Hermannshöhle (Hermann’s Cave) in Rübeland, 
Harz Mountains, Sachsen-Anhalt, Germany. In 
1956, more animals were brought to Rübeland. 
Originally all animals came from the Postojnska 
jama and were brought unlawfully to Rübeland 
(Völker  1981). A total of 20 animals were taken to 
Rübeland over a period of 25 years (Knolle et al. 
2016). In 2015, almost 60 years after the last 
animal had been put into the artificial lake in the 
cave, nine of the animals were still alive. 
 
 
Figure 1. The olm in Hermann’s Cave (photo: Harald 
Schütz). 
Slika 1. Močeril iz jame Hermannshöhle (foto: Harald 
Schütz). 
 
The situation in January 2015 was as follows: the 
total number of animals in Rübeland had dropped 
below 10. The sex of the animals was unclear, but 
there seemed to be only males. Reproduction or 
sexual activity had never been observed during 
more than 80 years. A decision was made to try to 
improve the conditions in order for the animals to 
reproduce. Since the olm is severely endangered, 
reproduction of the olms seemed an important 
objective. We also wanted to take the chance to 
inform the general public about this fascinating 
species, its origins and importance. First of all, 
gender determination of the animals was 
necessary. With the support of Olivier Guillaume 
from Moulis, France, we identified five females and 
four males. The determination of the sex was 
possible because all females bore eggs and males 
displayed aggressive behaviour.  Due to nature 
conservation there was no authorization to mark 
the animals individually. All animals were in good 
shape (Knolle et al. 2016). According to these 
results, it was decided to find a grant for the 
further investigation of the olms in Hermann’s 
Cave and for the optimization of the conditions of 
keeping it. 
 
The objectives of the project, which was supported 
by Lotto Sachsen-Anhalt and Tourismusbetrieb 
Stadt Oberharz am Brocken and was conducted by 
the Harz Speleological Working Group, were: 
accurate observation and care of the animals, 
improvement of conditions for the olms in 
Hermann’s Cave, documentation of the situation in 
the cave (films, photos), establishment of contacts 
and cooperation with experts abroad, and scientific 
exchange, all serving to preserve the animals in 
Rübeland. The project started in November 2015 
(Knolle et al. 2016). 
 
In the winter of 2015/2016, new hiding places 
were created in the pond. The animals started to 
display sexual behaviour (territorial, slightly 
aggressive, the females became larger) and we 
embarked on checking for eggs and 
spermatophores. In early February 2016, the first 
spermatophore was found and at the end of 
February the first egg was detected (Fig. 2). 
 
The eggs were distributed into small basins. 
Altogether, six eggs were found (Knolle et al. 
2016). Unfortunately, the eggs did not develop, 
with even the last egg drying out in late October 
2016. But the animals currently show territorial 
behaviour and seem to be ready to reproduce.  
 
We would like to cooperate more closely with the 
laboratories in charge of the olm. With the help of 
Anne IPSEN & Friedhart KNOLLE: The olm of Hermann's Cave, Harz Mountains... / »SOS Proteus« – FIELD NOTE 
NATURA SLOVENIAE 19(1): 51-52 
52 
experts from abroad we hope to further improve 
the conditions in Hermann’s Cave, if necessary. 
Our aim is to raise awareness among the general 
public for the needs of protecting this species. In 
the process we intend to promote the protection of 
other cave animals as well as the conservation of 
their habitats. We have applied for additional 
funding in order to study the olms more 
thoroughly, for example the animals could become 
the subject matter of a doctoral thesis.  
 
In the meantime the continuation of the project 
was ensured by finding a sponsor for another year 
of work. We will enhance our collaboration with 
the University of Halle-Wittenberg and other 
experts. 
 
Acknowledgements 
Gregor Aljančič, Hans-Christian Anger, Michael K. 
Brust, Holger Fraustein, Ute and Uwe Fricke, 
Dr. Wolf-Rüdiger Große, Olivier Guillaume, 
Wolfgang Hase, Cathleen Hensel, Ingeborg Kopp, 
Dr. Dieter Mucke, Michael Müller, Fritz Reinboth, 
Ernst Schuhose, Harald Schütz, Hannes Tschorn †, 
Christel and Reinhard Völker, Günter Volmer, 
Siegfried Wielert, Marion von Oppeln, Stefan 
Zaenker as well as the archives of ArGeKH, VdHK, 
Tourismusbetrieb der Stadt Oberharz am Brocken 
– Rübeländer Tropfsteinhöhlen, and the State 
Archives of Slovenia. 
 
References 
Knolle F., Puffe B., Ipsen A. (2016): 85 Jahre 
Grottenolme in der Hermannshöhle in Rübeland – 
Geschichte und Ausblick. Mitt. Verb. dt.  
Höhlen- u. Karstforscher 62(2): 47-54.  
http://www.vdhk.de [accessed on 7.3.2017]  
Völker R. (1981): Interessantes von den 
Grottenolmen in der Hermannshöhle Rübeland. 
Die Grotte 4(2): 27-28. 
 
 
Figure 2. Spermatophore and egg of the olm in Hermann’s Cave (photo: Ute Fricke). 
Slika 2. Spermatofor in jajce močerila v jami Hermannshöhle (foto: Ute Fricke).  
ca. 1.5 cm 
ca. 1 cm