hämähäkkieläimillä

Hämähäkkieläimillä is a Finnish term that translates to "Arachnida" in English, referring to the class of joint-legged invertebrate animals in the phylum Arthropoda. This class comprises over 100,000 described species and includes familiar creatures such as spiders, scorpions, mites, and ticks. Arachnids are characterized by having two main body segments, the prosoma (cephalothorax) and the opisthosoma (abdomen), and typically possess eight legs. Unlike insects, they do not have antennae or wings. Their exoskeleton provides protection and support, and they breathe through specialized organs called book lungs or tracheae.

The prosoma of arachnids usually bears the mouthparts, including chelicerae, which are often used for feeding, defense, or sensing. Pedipalps are another pair of appendages located near the mouthparts, which can have various functions, such as sensory perception, prey manipulation, or reproduction. The opisthosoma contains the digestive, reproductive, and excretory organs. Many arachnids are predatory, and their feeding strategies vary widely. Some, like spiders, spin webs to catch prey, while others actively hunt. Mites and ticks are often parasitic, feeding on plants or animals.

Arachnids inhabit a diverse range of environments, from terrestrial habitats like forests, deserts, and grasslands to aquatic and even marine settings. Their ecological roles are significant, contributing to food webs as both predators and prey. The study of arachnids is known as arachnology, a sub-discipline of zoology. Despite their often-feared reputation, most arachnids are harmless to humans and play vital roles in maintaining ecological balance.