Spiders are amazing creatures found all over the world.

There are over 51,000 species of spiders.

They live in almost every land habitat.

Spiders have eight legs and use sharp fangs to inject venom. They also have spinnerets to produce silk.

Most spiders eat insects, but some can catch birds and lizards.

They create intricate webs for hunting and protection. Their silk is strong and stretchy.

While some spiders have dangerous bites, most are harmless.

Spiders are important for controlling insect populations.

Etymology and Description

The term “spider” comes from the Old English word “spithra.” It evolved through Middle English as “spidhra.”

Spiders are arachnids, a type of arthropod with eight limbs. They belong to the class Chelicerates because of their chelicerae, which are appendages near the mouth that usually have fangs.

Spiders’ bodies have two main sections:

• The cephalothorax (prosoma)
• The abdomen (opisthosoma)

These two sections are connected by a narrow pedicel. Unlike insects, spiders have a fused thorax and abdomen.

Spiders have unique respiratory structures like book lungs and tracheal systems. They use venom to subdue their prey. Spinnerets at the end of the abdomen produce silk for webs.

There are different types of spiders, including:

• Jumping spiders
• Ground spiders
• Wolf spiders
• Dangerous ones like black widow spiders

Spiders’ silk is strong and elastic. It is used for creating egg sacs, hunting, and shelter. Their vision varies; for example, jumping spiders see very well.

Most spiders are harmless, but a few species can be risky for humans. Besides spiders, related arachnids like scorpions and the ancient liphistiidae also share the chelicerate lineage.

Spider Taxonomy and Classification

Spider classification is based on body structure, respiratory systems, and the types of silk they produce.

Spiders have two main body sections. The cephalothorax is a fusion of the head and thorax, and the abdomen is connected by a narrow pedicel.

Their legs and other parts, like pedipalps and fangs, help catch and eat prey.

DNA analysis has improved how we classify spiders and has revealed new species. This challenges older methods based mainly on physical traits.

The main groups in the Araneae order are:

1. Mygalomorphae (like tarantulas).
2. Araneomorphae (typical spiders).
3. Mesothelae (liphistiidae)

Common species include black widow spiders, hobo spiders, wolf spiders, and ground spiders.

Jumping spiders have great vision and unique hunting skills.

Spiders use silk from spinnerets for webs, egg sacs, and catching prey.

Their respiratory system includes book lungs and tracheal systems. They also have special digestive enzymes.

Most spiders, including eriophyid mites and common scorpions, are not dangerous to humans but are important for ecosystems.

Body Plan of Spiders

Circulation and Respiration

Spiders have a unique circulatory and respiratory system. They circulate oxygen using haemolymph, their blood-like fluid.

Their heart pumps haemolymph through an open circulatory system. Haemolymph flows freely in the hemocoel, the main body cavity.

Spiders have book lungs and sometimes a tracheal system for breathing.

• Book lungs have stacked, leaf-like structures in the opisthosoma where gases are exchanged.
• Tracheae are tubes that deliver oxygen directly to cells.

Different spiders, such as Liphistiidae, wolf spiders, and hobo spiders, use these systems to breathe.

Their body parts, the prosoma (cephalothorax) and opisthosoma (abdomen), are connected by a narrow pedicel. This connection helps internal functions.

Spider hearts are simple but effective. They support their predatory lifestyle by delivering oxygen efficiently.

In spider anatomy, good oxygen distribution helps them catch prey or conserve energy. This is true for species like tarantulas and jumping spiders.

Thanks to these respiratory and circulatory adaptations, spiders, including mygalomorphae and ground spiders, can live in many different environments.

Digestion and Excretion

Spiders are chelicerates. They start digestion outside their bodies. They inject digestive enzymes into their prey with their fangs. These enzymes turn the prey into a liquid. The spider then sucks up the meal.

Inside, the food goes to the midgut. Nutrients spread through a blood-like fluid called hemocoel. The digestive system runs from the thorax area to the abdomen. These sections are linked by a narrow part called the pedicel.

For waste, spiders use malpighian tubules and coxal glands. They remove nitrogenous waste and expel it near their spinnerets. Gaseous waste exits through spiracles in their abdomen.

Jumping spiders, wolf spiders, black widow spiders, and tarantulas use these processes. Hobo spiders and ground spiders do too. This system helps them digest food and remove waste. It is important for their survival in many environments, from plains to forests.

Central Nervous System

The central nervous system of spiders is in the prosoma, or cephalothorax. It mainly includes a brain and a ventral nerve cord. The brain, located in the prosoma, takes in signals from the eyes and other sensory organs. Ganglia along the ventral nerve cord control the legs and other limbs.

Spiders like hobo spiders and wolf spiders use this system for coordination in spinning webs, hunting, and using fangs to catch prey. The system helps manage body segments and tagmata through the pedicel’s fusion.

It controls functions like:

• Spinning silk using spinnerets
• Mating rituals involving chelicerae and pedipalps
• Releasing digestive enzymes

Compared to scorpions and ticks, spiders have more centralized nervous systems. This offers better control over web-building and jumping, especially in jumping spiders. Chelicerates like tarantulas and ground spiders use their advanced neural systems to adapt to their environments. This is supported by tracheal and book lung respiratory systems.

Sense Organs of Spiders

Eyes and Other Senses

Spiders have different kinds of eyes. These eyes help them hunt by detecting movement and light. For example, jumping spiders see very well. They can spot their prey clearly and pounce accurately.

Spiders also use other body parts to sense their surroundings. Pedipalps are located near their mouths and help them sense and handle prey. Spinnerets make silk for webs, which help trap prey and sense vibrations from struggling insects.

Spider fangs inject venom into their prey. This venom turns the prey into a digestible liquid using digestive enzymes. Spiders breathe using systems like tracheal tubes and book lungs. Wolf spiders and ground spiders detect prey by feeling vibrations through the web or ground, even when it’s windy.

Spiders communicate to find mates and avoid predators. They sense chemical signals with special receptors. These receptors detect pheromones from other spiders, which is important during mating. Black widow spiders and tarantulas use chemical signals to avoid becoming prey.

Spiders have different body sections, such as the cephalothorax and abdomen. These body parts help them adapt to various environments. This showcases their wide range of sensory skills across many species.

Spider Locomotion

Spiders move by pumping fluid into their legs. This extends their legs and allows them to move.

Different species move in different ways:

• Wolf Spiders run fast.
• Jumping Spiders leap quickly.

Spiders have eight segmented limbs. Strong muscles attach these limbs to the prosoma, the front section of their body.

Their unique leg structure includes chelicerae and pedipalps near the fangs. This setup helps them move and capture prey. The legs have multiple segments, giving them flexibility and strength.

The hydraulic and tracheal systems help them move efficiently on different surfaces:

• Ground Spiders run quickly to chase prey.
• Web-spinners like the Black Widow create webs to catch food.

Hobo spiders and Tarantulas use their strong legs to move on various terrains. Their fangs, which are linked to venom glands in the chelicerae, help them immobilize prey.

Spinnerets at the end of the abdomen produce silk. This silk is used to create webs, egg sacs, and other structures.

Silk Production and Web Weaving

Spiders make silk using spinnerets found in the lower part of their body, called the opisthosoma.

This silk comes in different types, each made for specific uses. Capture silk is sticky and used for trapping prey. Dragline silk forms the frame of the web.

Spiders begin making webs by releasing a silk thread into the wind to anchor a line. They then add radial and spiral sections. Different species have different web styles. Orb-weavers create circular webs, while hobo and wolf spiders make funnel-shaped webs. Jumping spiders use silk for safety lines.

Silk and webs have many uses. They help catch prey, create shelters, wrap eggs in protective sacs, and serve as safety lines to prevent falls.

Spiders have a thorax and abdomen connected by a narrow part called a pedicel. They are chelicerates, meaning they have special mouthparts called chelicerae and pedipalps to handle prey.

Spiders breathe using book lungs or a tracheal system. They are skilled hunters due to these adaptations and their venomous fangs.

Reproduction in Spiders

Spiders have interesting courtship behaviors. Males use different methods to identify themselves to females. For example:

• Jumping spiders use visual displays.
• Wolf spiders use vibrations.

During mating, the male transfers sperm using his pedipalps. Females lay eggs in silk sacs. These sacs are hidden in webs or underground. They protect the eggs from predators and harsh weather.

The egg development stages include fertilization and growth inside the egg sac. Eventually, spiderlings hatch. Some female spiders, like ground spiders and tarantulas, guard their egg sacs. This ensures a secure environment until hatching. Some species, like wolf spiders, carry their egg sacs with them to keep the eggs safe.

After the eggs hatch, spiderlings stay with their mother for a while. This helps them gain strength before going out on their own.

Spiders are chelicerates and have a tracheal system for breathing. Their bodies are divided into two sections:

• Prosoma
• Opisthosoma

These sections are connected by a narrow pedicel. Spiders use venom from their fangs (chelicerae) to catch prey. The venom injects digestive enzymes to break down the food.

Feeding Habits of Spiders

What Do Spiders Eat?

Spiders are arachnids. They eat insects, birds, and lizards. They use eight limbs, spinnerets for silk, and venomous fangs to capture and eat prey.

Many spiders spin webs to trap their prey. Jumping spiders and wolf spiders use ambush tactics. Web-builders rely on strong silk and intricate designs to catch flying insects. Ground spiders and tarantulas hunt actively instead of using webs.

When spiders catch prey, they inject venom to immobilize it. Then, they use digestive enzymes to break down the meal. Different spider species have different diets. For example, hobo spiders mostly eat insects, while mygalomorphae might eat small vertebrates.

Spiders have two body sections: the thorax and the abdomen. They use advanced eyes, pedipalps, and other parts to detect and capture prey. Their breathing methods vary. Some use book lungs, others use tracheal systems. This helps with their different hunting techniques.

For instance, black widow spiders are known for their venomous bite and ability to catch larger prey.

Spiders vs. Other Arachnids: Ticks and Scorpions

Spiders, ticks, and scorpions are all arachnids, but they look different.

Spiders have two main body parts: a cephalothorax and an abdomen, joined by a thin connector. Scorpions have a broad tagma joining their prosoma and opisthosoma. Spiders use spinnerets to make silk for their webs. They have fangs with venom. Scorpions have stingers at the end of their tails for venom. Ticks latch onto hosts to drink blood.

Spiders often make webs to catch prey. Wolf spiders and jumping spiders hunt without webs. Scorpions use pincers and stingers to catch prey and usually hunt at night. Ticks wait on plants to latch onto hosts.

Spiders mostly eat insects but can also eat birds and lizards. They inject venom and enzymes to turn their prey into liquid. Scorpions hunt insects and small animals using their pincers and sting. Ticks drink blood from hosts over several days. Spiders like black widows and tarantulas use venom mainly for feeding or defense, despite their scary reputation.

FAQ

What are some common types of spiders found in households?

Some common types of spiders found in households include cellar spiders, house spiders, and wolf spiders. Vacuuming, sealing cracks, and removing clutter can help prevent infestations.

How do spiders create their webs?

Spiders create their webs by secreting silk from spinnerets located at the back of their abdomen. They use their legs to manipulate the silk and build intricate patterns like orb webs or funnel webs for catching prey.

What purpose do spider webs serve?

Spider webs serve to catch prey for the spider to eat, provide shelter and protection, and aid in reproduction. They also help spiders communicate through vibrations. For example, orb-weaving spiders use their webs to catch flying insects, while funnel-web spiders use their silky homes as burrows.

Are all spider webs the same?

No, spider webs vary in shape, size, and structure depending on the species of spider. For example, orb-weaver spiders create intricate circular webs, while funnel-web spiders build funnel-shaped webs.

How can I prevent spiders from building webs in my home?

Regularly clean and vacuum to remove spider webs and eggs. Seal cracks and crevices in walls, windows, and doors. Use citrus-scented cleaners or essential oils like peppermint, lavender, or tea tree to deter spiders.