Family portraits

Even though spiders are arachnids in our collective psyche, they are not the most common with 47,714 species described today.

In fact, with more than 55,000 recorded species,mites (including ticks) comprise a major arachnid subclass. Opiliones (6,676 spp.), pseudoscorpions (3,788 spp.), scorpions (2,526 spp.) and Solifugae (1,146 spp.) follow far behind. Finally, mention should be made of much more restricted groups such as Schizomida (358 spp.), Amblypygi (217 spp.), Thelyphonida (120 spp.), Palpigrades (109 spp.) and Ricinulei (89 spp.). However, the class Arachnida has about 20 times as many species as mammals.

Spiders: produce silk from glands in the abdomen

Amblypygi: have an anterior pair of long, whip-like walking legs

Thelyphonida: spray a toxic mixture from their anal glands

Schizomida: their prosoma has a dorsal surface divided into small plates

Palpigrades: use their pedipalps to walk

Ricinulei: have a uniquehood-like structure covering their chelicerae and mouth.

Mites: are cosmopolitan and have very generalised feeding habits

Opiliones: have scent glands that can repel predators

Scorpions: have sensory combs on the underside of their abdomen

Pseudoscorpions: produce silk and venom from their chelicerae

Solifugae: have sucking organs on their pedipalps

Did you know that the name “arachnid” comes from the Greek “arachné” which means spider? In mythology, Arachné was the name of a young woman who excelled in the art of weaving and who claimed to be a finer weaver than the goddess Athena herself. During a contest
in which Athena destroyed Arachne’s work, she decided to hang herself. Athena decided to grant Arachne a second life by transforming her into a spider hanging from threads so that she could weave for eternity.