Caves provide highly specialized living conditions for their inhabitants. The environmental conditions are unusually stable: temperature and humidity change very little. Plants cannot exist in caves because of the lack of light, and thus food is scarce for animals as well. Accordingly only a very few specialized species can exist in the stringent conditions found in caves.
In the caves of Naxos lives an interesting insect: the endemic Cave Cricket Dolichopoda naxia. The Southern European genus Dolichopoda consists of about 30 species. Each of these occurs only in a small area, sometimes only in one single cave. In the hot and dry climate we have nowadays in the Mediterranean area, the sensitive animals cannot survive outside their caves and so they can no longer reach other caves. Thus the populations of different caves are isolated from each other. Their geographic isolation led to the emergence of many different species in a relatively small area. The Cave Crickets came into the Aegean probably about 5,5 million years ago during the miocene age. Genetic analyses indicate that the Naxian species has been isolated for about 3 million years. Its closest relatives live on Samos and Kalimnos, while larger differences may be found in the more distant Cretan species.
Cave Crickets belong to the order Ensifera (crickets, katydids and bush crickets) which are characterized by their long antennae. The antennae―and also the legs of the Cave Crickets―are especially long. Cave Crickets can jump, but they usually just walk rather slowly. In their long adaptation to underground life their wings became very much reduced and they cannot fly. As a consequence they cannot chirp either (the Ensifera produce their songs by rubbing their wings), and accordingly they have also lost their hearing organs. The females can be identified by their long ovipositor.
Crickets develop by an incomplete metamorphosis (hemimetabolism), which means that the larvae resemble the adults from the beginning and grow gradually more alike them with each moulting. In one year the larvae moult about ten times. The adults live only one year. Cave Crickets are omnivorous: in this environment with very little food they have to take whatever they can get.
On Naxos the Cave Crickets occur also in the emery mines which often correspond to natural caves. They can only be found in larger numbers in places with sufficient humidity.
Emery mines below Kóronos; the mine where we found the most Cave Crickets lies behind the tree visible in the back of the picture above the truck.
the entrance to the mine
in the mine
Numerous Cave Crickets sit on the walls and especially under the roof.
The brownish animals have no wings but very long legs and antennae.
female with ovipositor
The small larva already resembles the adult.