Why do people call spiders arachnids?


Spiders are among the most fascinating creatures in the world. They are usually feared and avoided due to their creepy appearance and venomous nature. However, despite their unique features and behavior, many people refer to them as arachnids. This article seeks to explore why spiders are usually classified as arachnids.

What are arachnids?

Arachnids are a class of joint-legged invertebrates that includes spiders, scorpions, ticks, and mites. They are members of the phylum Arthropoda, which is characterized by their hard exoskeletons, jointed limbs, and segmented bodies. Arachnids have two main body parts, the cephalothorax, which contains the head and thorax, and the abdomen. They are usually small in size, and their habitats vary from water to land, and even air.

Characteristics of arachnids

Arachnids are known for their unique characteristics that distinguish them from other invertebrates. One of the most noticeable features is their eight legs, which they use for walking, jumping, and hunting prey. Unlike insects, which have three body segments, arachnids have two. They also have chelicerae, which are specialized mouthparts that help them inject venom into their prey. Arachnids also have spinnerets, which they use to produce silk, a protein fiber used for web building, reproduction, and protection.

What are spiders?

Spiders are a type of arachnid that belong to the order Araneae. They are characterized by their eight legs, two main body parts, and the ability to produce silk. Spiders are found in almost all habitats worldwide, ranging from deserts, forests, oceans, and even human homes. They are predators that feed on other insects and small animals, and their venom is used to immobilize and digest their prey.

Similarities between spiders and arachnids

Spiders share many characteristics with other arachnids. They all have an exoskeleton, jointed legs, and segmented bodies. They also have specialized mouthparts called chelicerae, which are used to deliver venom. Spiders and other arachnids also have respiratory systems that consist of book lungs or tracheae, depending on the species.

Differences between spiders and arachnids

While spiders are a type of arachnid, they differ from other members of the class in several ways. Unlike scorpions, ticks, and mites, spiders do not have pincers or claws. They also have an extra pair of spinnerets, which they use to produce different types of silk for various purposes. Spiders are also more diverse in terms of their size, color, and behavior than other arachnids.

Taxonomy of spiders and arachnids

Spiders and other arachnids are classified under the phylum Arthropoda, which is further divided into classes, orders, families, genera, and species. The class Arachnida is divided into eleven orders, including the order Araneae, which comprises all spiders. Within the order Araneae, spiders are further divided into families based on their physical characteristics and behavior.

Misconceptions about arachnids

There are many misconceptions about arachnids, including spiders. Many people believe that all arachnids are venomous, but this is not true. Some arachnids, such as whip scorpions, do not produce venom. Another common misconception is that all spiders build webs to catch prey. While web-building is a common behavior among spiders, not all species do so. Some, like wolf spiders, hunt their prey without using webs.

Why spiders are considered arachnids

Spiders are classified as arachnids because they share many similarities with other members of the class. They have eight legs, two main body segments, chelicerae, spinnerets, and respiratory systems that resemble those of other arachnids. As such, they are considered a distinct order within the class Arachnida.


In conclusion, spiders are classified as arachnids because of their unique physical characteristics and behavior, which are shared with other members of the class. Despite misconceptions about arachnids, spiders are fascinating creatures that play a crucial role in maintaining the ecosystem. Understanding their classification and taxonomy can help us appreciate their significance and importance in the natural world.

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