Spindeldjur

Spindeldjur, belonging to the class Arachnida, is a diverse group of arthropods that also includes spiders, scorpions, mites, and ticks. They are characterized by having eight legs, a body divided into two main segments (cephalothorax and abdomen), and the absence of antennae. This body plan distinguishes them from insects, which typically have six legs and three body segments. Spindeldjur respire through book lungs or tracheae.

Their feeding habits are varied. Many spindeldjur are predatory, utilizing venom to subdue prey, while others are parasitic, feeding on the blood or tissues of other animals. Some species are herbivores or detritivores. Reproduction in spindeldjur generally involves sexual reproduction, with males transferring sperm to females. The young often hatch from eggs and may undergo several molts as they develop, sometimes passing through nymphal stages before reaching adulthood.

Spindeldjur inhabit a wide range of environments, from deserts and forests to aquatic habitats and even human dwellings. Their ecological roles are significant; predators help control insect populations, while parasites can transmit diseases. The diversity within this group is immense, with hundreds of thousands of described species, and it is estimated that many more remain undiscovered. Their evolutionary history is ancient, with fossils dating back to the Devonian period.