What are four types of arachnid?

There are eleven different types of identified arachnids. The four most identifiable are

1. Spiders (obviously)

2. scorpians

3. ticks and mites

4. solpugids (such as the Giant Egyptian Camel spider, which is not a true spider at all.)

Tarantulas, although commonly categorised as spiders, are also a species of non-spider arachnid.