For collectors of ancient coins it can be a dream to find a Cyclocosmia, with this fashion of offering coins with errors or old coins on buying and selling applications, finding a coin this rare can generate good income.
With an approximate diameter of one euro cent, black in color, similar to old iron, and irregular patterns that, with the naked eye, cannot be seen in detail. Without a doubt an opportunity not only for collectors, but also for lovers of rarities. But what makes it so special? It moves alone.
With so much technology advancing, it seems surprising to find an old coin that moves on its own, although In reality it is not a coin, but the opisthosoma of spiders of the genus Cyclocosmia.
The genus ‘Cyclocosmia’
To the surprise of many, this little spider friend has yet to be found. Until 2005, only four had been identified: three in North America and the other in China. However, in recent years, several investigations have brought to light up to seven more species, present in different places in Southeast Asia, until then unknown.
One of the reasons why there are few species, is because they have very demanding habitat requirements and with camouflage capacity different from that of other spiders. Furthermore, they do not spread their web on the branches of trees, but rather dig holes in the ground, where they set traps for their prey.
In addition, this species is known for its opisthosomal disc, which is hard and firm, which can resemble a coin or another type of ancient relic. Why?
In the opisthosomal disc of a ‘coin spider’ there are several details. On the external part of the disc, a series of grooves stand out in a radial direction, creating a faintly lobed margin. In the center, three pairs of ovoid structures, arranged symmetrically, run through the area from top to bottom, in decreasing size – the upper ones are the largest – and between them, a series of rounded nodules complete the pattern, the shape of which varies between species. and even between specimens.
Another feature of this spider is that the exoskeleton of the shield is very thick, and strong muscles are necessary to support it. Furthermore, since the opisthosoma is shorter than other spiders, these muscles must be shorter than usual, which must be compensated for with greater thickness.
It’s still an unknown world
Little is known about the reproductive habits of this group of spiders and most of it has been discovered recently.
In fact, during a research that allowed the discovery of Ciclocosmia ruyi, egg capsules were obtained, which were studied and raised in the laboratory. This allowed us to know the details of development, and particularly, to discover that the opisthosomal disc, its most characteristic feature, is formed during the second larval stage.
An important fact, since these discs have a defensive function. And this truncated and flattened opisthosoma like a coin serves as a shield.