Arachnids belong to the phylum Arthropoda, a group of arthropods. They are characterized by having four pairs of legs, an abdomen, and an exoskeleton. There are more than 100,000 species of arachnids. Some arachnids are parasites, while others are predators.
The word “arachnid” originates from the Old English verb spinnan, meaning to spin. During the early stages of their life cycle, arachnids have two major divisions, called the cephalothorax and the abdomen. These two sections are separated by a pharynx, which acts as a pump. Several groups of arachnids also secrete venom.
Depending on the species, an arachnid may have four pairs of legs or eight pairs. Some arachnids have eggs on their abdomen. Other arachnids have cocoons. Most arachnids live only one year. In colder climates, some groups live longer than a year.
Throughout their lifetime, arachnids are carnivorous. They eat small animals, including insects and small rodents. They can also eat their own silk. When their prey is ready to die, arachnids suck up the liquid parts and digest them outside of their bodies.
Many arachnids can detect light and dark. In addition, arachnids have special sensory organs and excretory structures.
The hard exoskeleton of arachnids aids in maintaining moisture. The skeleton of an immature arachnid is not very strong, so it’s important for spiders to find a suitable host. Ticks are the most common arachnids, and they are also parasites. Several species of ticks are venomous.
Spiders are part of an ancient group of creatures, called Arachnida. This group includes scorpions, mites, and other arachnids.