Which insect order includes both spiders and ticks?

The order that includes both spiders and ticks is Arachnida. This classification is significant because it encompasses a diverse group of arthropods characterized by having eight legs, which distinguishes them from insects, which have six legs. Arachnids also have bodies divided into two main parts: the cephalothorax (combination of the head and thorax) and the abdomen.

Spiders, known for their ability to produce silk, are a well-known member of this order, while ticks are important for their roles as pests and vectors of disease. Understanding that Arachnida also includes other species such as scorpions and mites highlights its broad ecological impact.

In contrast, Crustacea refers to a group of primarily aquatic arthropods like crabs and lobsters, which do not include spiders or ticks. Diplopoda encompasses the millipedes, characterized by their elongated bodies and numerous legs, which again do not fall under the same classification as the mentioned arachnids. Insecta, on the other hand, refers specifically to insects, which are a different class of arthropods with distinct characteristics such as three body sections and six legs, thereby excluding spiders and ticks.