Prospekt Fauna, Intresting facts

Photo 1. The star-shaped web of a star-web spider (Uroctea durandi), hiding in the crack of a decayed oak trunk (Photo by M. Randić)


There are many different species of spiders in Učka Nature Park. Some types of spiders can even be found in the wintertime, in shady spots where the ground is frozen. One such spider is the star-web spider (Uroctea durandi), which tends to hide in small, star-shaped webs underneath stones or in cracks in rock. We have already written about the star-web spider on our Web pages (http://www.ju-priroda.hr/zanimljivosti.asp?iddb=220  )…

During the winter, many spider species hide under stones, inside clumps of grass or beneath the bark of dried trees. Others survive the cold season wrapped in a cocoon that they make from dense silk threads to give them better protection. In many cases the characteristic shapes and thread quality of these sacs or cocoons can help us identify the group to which the spider belongs but only rarely will we be able to immediately guess the spider’s species.

That, however, is not a problem when it comes to an interesting spider from the family Oecobidae (also known as disc-web spiders) that spins a dense web out of white threads. The web is characteristically flat and star-shaped, and about three to four centimetres wide. Once we learn to identify the shape of this web, there will be no mistaking the type of spider hiding in it (Photos 1, 2 and 3). Because the web is densely spun, the spider inside is not immediately visible. However, if the web is not empty or abandoned, we can easily lure the spider out by gently touching and pressing on the web from its centre toward the edges. Providing the spider is not in a state of complete torpor due to the cold, it will probably come running out (Photo 3). If we see that the spider is black with five distinctly yellow spots on the back part of its body, we can be sure that we guessed correctly that it is a star-web spider.

This spider can often be found indoors as well as outdoors. The spider is black and, because of its five distinct yellow spots, many people are afraid of it, thinking it is poisonous and dangerous (Photo 3). Although all spiders are venomous, this species, together with most spider species (with the exception of the lethal black widow and a few other particularly large and dangerous species), is actually harmless to people. This is because the chelicerae they use to inject venom into their victims are too small and too weak to puncture human skin.

While walking along the Land Art Trail in Učka Nature Park one lovely, sunny day (17 December 2016), we discovered the web of a star-web spider with a live and vivacious spider inside, under a stone on the edge of an overlook below Stražica Hill. When we touched the web, the spider ran out. Under the stone we also found a crab spider that does not build any kind of web. We came across these spiders and many other interesting things during a mountaineering workshop organized for pupils who are members of the Tuhobić Mountain Club at the elementary schools of Zamet and Vojak. The children received their first lessons in outdoors orientation at the workshop.

Marko Randić

Photo 2. If we peel back a small piece of bark from a dried tree trunk, we are likely to see the web of a star-web spider. In the photo we can see the threads that spread outwards from the star-shaped edges of the web. These threads enable the spider to ‘communicate’ with its environment and they signal the approach and movement of the tiny animals on which the spider preys. (Photo by M. Randić).

Photo 3. A star-web spider on its web. This is not the spider’s usual position, because it tends to spend most of the time hidden within the web. The star-shaped web has ten ‘tentacle-like’ extensions through which the spider gathers information about the movements of tiny animals, its potential prey. (Photo by M. Randić)