Spiders and alies (Araneae etc.)

Special thanks to Bryan Goethals(B), Aloys Staudt (D), Jürgen Peters (D), Guido Bonami(B), Gerard Brady (GB), GT Rice (USA), Lidy and André de Laet-Smet (B) and Kurt Stueber (D) for their help in identifying various species.

This page has been split up in 5 smaller ones in November 2004, for it grew too big. Especially modem users had to wait a long time for the page to load completely. Should you be looking for a particular animal of family, please choose from the options in the picture menu above, use our search engine near the bottom of the page or choose an option below:

1 House Spiders, 2 Garden Spiders, 3 Mites and Ticks, 4 Harvestmen, 5 Pseudoscorpions

Introduction to spider like arthropods

It is considered to be easy: all small animals with 6 legs are insects and all small animals with 8 legs are spider like arthropods. But actually possessing 8 legs do not mean that these animals are closely related as the insects are. Yet it is a practical solution to separate the huge amount of species found in insects. Small animals walking on 8 legs are usually well known: spiders, harvestmen, scorpions and ticks. Yet the animals differ considerably from oneanother. Spiders have a body consisting of three parts, like insects have: head, thorax and abdomen. The head and thorax however have fused into one visible structure called the cephalothorax. Ticks have only two bodyparts: head and body. Harvestmen even consist of one part, the body, only. From this it is obvious these animals are not closely related at all. Oh, by the way: even these 8 legs are not always there. A newly born mite or tick has 6 legs only. Worldwide there are many spiders indeed. The number of mites is considerably as well, even though many are rarely ever seen. They are small and most are parasites to mammals, birds or insects. There are far less harvestmen species. Of the pseudoscorpions only some 15 species are present in the Benelux. Many spiders and harvestmen are quite big. Pseudoscorpions and mites are much smaller. Many species can hardly be seen by the naked eye.

The House Spider to the left is a true giant, reaching some 18 mm. Mites, like the ones on the bumblebee to the right, often hardly reach a length of one millimeter.

Spiders belong to the arthropods, just like insects and many other animals do. Many people therefor think spiders are insects, but that is not true. Spiders have 8 legs, insects only 6. Spiders have 6 or 8 ordinary eyes, insects have two compound eyes. Despite the fact they are relatively small, spiders are more related to scorpions and crabs. Many spiders, though not all, are capable of producing threads. Some use these wires to enwrap the eggs or young. Other species produce a web used to catch prey. Below the web one can sometimes find a bone yard: parts of insects the spider can not eat, such as legs or wings. Especially below the web of the vibrating spiders heaps of body parts may be encountered.

To the left: spiders may be quite beautiful, most of us find them scary! To the right a bone yard below the web of possibly an vibrating spider.

Spiders are not among the easiest animals to identify. Many bear no markins, or if they do the markings are identical to those of other species. The colours are just as useless in many cases. Young animals may have colours different from the adults and many spiders have either a variable colour, such as the European Garden Spider and the Goldenrod Crab Spider, or show indistinct colouring. Adult female spiders however can be identified by looking at the epigyne. This is the part of the sexual organs outside the spider's body. Sometimes one needs a microscope to see it, but in other cases it is visible to the naked eye. Especially orb-web spiders have an epigyne that is easy to see. This little organ is situated in a rather peculiar place: somewhere half way the body, just behind the legs. You probably expected it somewhere near the end of the body, for that's the place the sexual organs are in insects for instance. However the organs situated at the end of a spider's body are the spinnerets which the spider uses to produce its threads.

To the left the spinnerets, to right the epigyne, just behind the legs. In this case both belong to the European Garden Spider.

Many people have arachnophobia. Or, to put it plainly, they have a fear of spiders. In Europe especially this is unfair. Only very few spiders are capable of penetrating the human skin. Those which can, will only bite of handled carelessly. Besides spiders are very useful animals by controling the number of insects. Without spiders we wouldn't be able to go outside in summer due to the number of mosquitoes, gnats, flies and wasps. Also mites are quite usseful, for many species eat aphids. Some mites however are a nuissance. They suck blood from mammals, birds or insects. Man suffers from the tick and another mite is very harmful to bee keepers. Pseudoscorpions are too small to be a bother to us. Besides they are all active hunters, just like the harvsetmen. Some daddy long legs are even used in agriculture to eat harmful insects.

Both the small pseudoscorpion to the left and the much bigger harvestmam to the right are active hunters.

Pictures © Hans Arentsen (info@gardensafari.net) en © Hania Arentsen (photog@gardensafari.net).

Also visit Hania's Photographer's Pages, including pictures from Holland, Germany, China, the USA and Malaysia.